DTE Electric Company v. Toshiba American Energy Systems Corporation

              UNITED STATES DISTRICT COURT                              
              EASTERN DISTRICT OF MICHIGAN                              
                    SOUTHERN DIVISION                                   

CONSUMERS ENERGY CO. and                                                  
DTE ELECTRIC CO.,                                                         

   Plaintiffs,                                                          
                                      Case No. 22-10847                 
v.                                                                        
                                      Hon. F. Kay Behm                  
TOSHIBA AMERICA ENERGY                                                    
SYSTEMS CORP. and                                                         
TOSHIBA CORP.,                                                            

   Defendants.                                                          
_________________________________/                                        


         OPINION AND ORDER REGARDING MOTIONS                            
         IN LIMINE TO EXCLUDE EXPERT TESTIMONY                          

   Before the court are several motions in limine to exclude expert     
testimony filed by both sides. The parties largely challenge excerpts of  
testimony or opinions rather than seeking to exclude the experts entirely. In 
general, the court finds that the parties’ criticisms of the experts are  
relevant to the weight and credibility of their testimony, rather than its 
admissibility. Provisionally, the court addresses the parties’ motions as 
discussed below, with final rulings to be issued as necessary in the context 
of the evidence as it is introduced at trial.                             
I.   Factual Background                                                 

   This breach of contract action arises from repairs made to the       
Ludington Pumped Storage Plant, which is a hydroelectric plant consisting 
of six pump-turbines. The plant is owned by DTE Electric Company and      
Consumers Energy Company (“Utilities” or “Owner”). They contracted with   

Toshiba Energy Systems Corporation (“TAES”) in 2010 to overhaul the       
plant (“Contract”). TAES’s parent company, Toshiba Corporation, provided a 
guaranty with respect to the Contract. The Contract provides that the TAES 
would “return the Plant to as nearly an as new condition as possible” and 

allow the plant to operate with a “minimum thirty (30)-year service life” with 
“only minimal routine maintenance.” ECF No. 217-2 at PageID.21067,        
21081-82.                                                                 

   Plaintiffs allege that TAES’s work is defective in multiple respects. 
One defect involves “discharge rings” and “discharge ring extensions”     
(“DREs”), which are large steel rings that comprise part of the water     
passage directing water through each unit. They form a pressure boundary  

holding the water inside each unit. In particular, Plaintiffs allege that TAES 
removed, and did not replace, a stainless-steel overlay for the discharge 
rings, which protected the carbon steel material. Plaintiffs also allege that 

the metal TAES selected for the DREs is not suitable and that TAES’s      
construction methods placed the DREs under excessive stress, causing      
cracks. According to Plaintiffs, they notified TAES of this defective work with 

respect to Units 2 and 4 in 2019. They also allege that DREs in other Units 
experienced cracking, leaking shaft seals, and failing motor operated     
disconnect (“MOD”) switches. Plaintiffs asked TAES to remedy these        

defects, but TAES did not do so. According to Plaintiffs, TAES attempted  
temporary repairs that did not fix the problems. Plaintiffs contend that they 
continued to ask TAES to repair its defective work several times in 2021  
and 2022, to no avail.                                                    

   Plaintiffs allege that the problems arising from TAES’s defective work 
have worsened since they filed this action in 2022. They have contracted  
with Voith Hydro to assess TAES’s work and develop a repair plan.         

Plaintiffs contend that the damage to Units 2 and 4 is such that they have 
been required to significantly limit the use of those units; in 2025 their use 
is limited to approximately 50 hours per year. In 2024, Defendants        
proposed a repair plan, but the Utilities rejected it, contending that it would 

not address all of the problems and relied on an untested approach that   
would require “jacking up” the runner. ECF No. 229-24.                    
   Both sides have identified several expert witnesses as well as       

challenges to those witnesses, as discussed below.                        
II.  Law and Analysis                                                   

     A. Admissibility of Expert Testimony                               

   The admissibility of expert testimony is governed by Federal Rule of 
Evidence 702:                                                             
     A witness who is qualified as an expert by knowledge, skill,       
     experience, training, or education may testify in the form of      
     an opinion or otherwise if the proponent demonstrates to           
     the court that it is more likely than not that:                    

      (a) the expert’s scientific, technical, or other specialized      
      knowledge will help the trier of fact to understand the           
      evidence or to determine a fact in issue;                         
      (b) the testimony is based on sufficient facts or data;           
      (c) the testimony is the product of reliable principles and       
      methods; and                                                      
      (d) the expert’s opinion reflects a reliable application of       
      the principles and methods to the facts of the case.              

Fed. R. Evid. 702. The trial judge is tasked with “ensuring that an expert’s 
testimony both rests on a reliable foundation and is relevant to the task at 
hand.” Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579, 597    
(1993); see also Babb v. Maryville Anesthesiologists P.C., 942 F.3d 308,  
316 (6th Cir. 2019) (noting that courts consider whether the witness is   
“qualified” and whether the testimony is “relevant” and “reliable”).      
   The relevancy threshold under Rule 702 “is low,” requiring only that 
the testimony “logically advances a material aspect of the proposing party’s 
case.” United States v. LaVictor, 848 F.3d 428, 442 (6th Cir. 2017) (cleaned 
up; citation omitted); see also United States v. Bonds, 12 F.3d 540, 557 (6th 

Cir. 1993) (explaining that the relevance inquiry asks whether the evidence 
relates to “any issue in the case”).                                      
   In Daubert, the Supreme Court discussed factors that may be helpful  

in determining the reliability of a particular scientific “theory or technique,” 
such as testing, peer review, error rates, and “acceptability” in the relevant 
scientific community. Daubert, 509 U.S. at 593-94. Although the specific  
Daubert factors may not be applicable with respect to non-scientific      

experts, the court nonetheless must exercise its “gatekeeping” function to 
assess the reliability of other types of expert testimony, such as that based 
upon “other specialized knowledge.” Id.; Fed. R. Evid. 702. “[T]he test of 

reliability is ‘flexible,’ and Daubert’s list of specific factors neither 
necessarily nor exclusively applies to all experts or in every case. Rather, 
the law grants a district court the same broad latitude when it decides how 
to determine reliability as it enjoys in respect to its ultimate reliability 

determination.” Kumho Tire Co. v. Carmichael, 526 U.S. 137, 141-42        
(1999) (emphasis in original). Where non-scientific expert testimony is   
involved, “the [Daubert] factors may be pertinent,” or “the relevant reliability 

concerns may focus upon personal knowledge or experience.” Surles ex      
rel. Johnson v. Greyhound Lines, Inc., 474 F.3d 288, 295 (6th Cir. 2007)  
(citations omitted).                                                      

   “The task for the district court in deciding whether an expert’s opinion 
is reliable is not to determine whether it is correct, but rather to determine 
whether it rests upon a reliable foundation, as opposed to, say,          

unsupported speculation.” In re Scrap Metal Antitrust Litig., 527 F.3d 517, 
529-30 (6th Cir. 2008). In considering the admissibility of expert testimony, 
the court bears in mind that “rejection of expert testimony is the exception, 
rather than the rule,” and that “mere weaknesses in the factual basis of an 

expert witness’ opinion ... bear on the weight of the evidence rather than on 
its admissibility.” Id. at 530-31. Rather than exclusion, “[v]igorous cross-
examination, presentation of contrary evidence, and careful instruction on 

the burden of proof are the traditional and appropriate means of attacking 
shaky but admissible evidence.” Daubert, 509 U.S. at 596.                 
     B. Plaintiffs’ Motion to Exclude Certain Opinions                  
        of Bernhard Bittner (ECF No. 206)                               

   Plaintiffs seek to exclude certain testimony from Defendants’ expert, 
Berhard Bittner, on relevancy grounds. Specifically, Plaintiffs seek to   
preclude Bittner from testifying that Plaintiffs improperly maintained and 
operated the MOD switches. Plaintiffs allege that the MOD switches are    
defective, have failed repeatedly, show signs of degradation, and will not 
meet the anticipated 30-year service life of the plant overhaul. Plaintiffs 
argue that Bittner’s opinion is not relevant because he does not identify a 

causal connection between the improper maintenance and the problems       
Plaintiffs have experienced with the MOD switches, such as the bent guide 
rails.                                                                    

   Defendants respond that Plaintiffs have mischaracterized Bittner’s   
testimony and that his opinion on improper maintenance is relevant to both 
the MOD switch problems and Plaintiffs’ claim that they are contractually 
entitled to a 30-year service life. Bittner opined that Plaintiffs 1) improperly 

greased the MOD switch guide rails, which “is detrimental to the rolling  
motion of the guide rollers”; 2) improperly used the MOD switch to set a  
limit switch, which resulted in “audible grinding of the drive gears,” and 

would lead to abnormal wear of the components; 3) operated the switches   
in a manner “causing electric arcing and subsequent degradation on the    
contacts of the MODS”; and 4) could not provide records of maintenance    
for the MOD switches, violating the recommended practices of certain      

electrical codes. Defendants intend to use this testimony to rebut that of 
Plaintiffs’ expert, Dr. John Martens, and Plaintiffs’ allegation that the MOD 
switches are defective. Plaintiffs argue that Bittner’s testimony is not  

relevant because he does not assert a causal connection between the       
improper use and maintenance and the malfunctions experienced by          
Plaintiffs.                                                               

   However, Bittner need not definitively opine on causation for his    
testimony to be relevant, which is a “low” bar. See LaVictor, 848 F.3d at 
442. “Daubert and Rule 702 require only that the expert testimony be      

derived from inferences based on a scientific method and that those       
inferences be derived from the facts of the case at hand, not that they know 
answers to all the questions a case presents—even to the most             
fundamental questions.” Jahn v. Equine Servs., PSC, 233 F.3d 382, 390     

(6th Cir. 2000) (citation omitted) (emphasis in original). Dr. Martens    
observed that problems with the MOD switches included excessive wear,     
“bent guide rails, misaligned contacts, and mechanical instability.” ECF No. 

228-6 at PageID.25534-35. He also noted that the MODS “were required to   
have a lifetime of 30 years.” Id. at 25554. Defendants may use Bittner’s  
testimony to rebut Dr. Martens’ report, provide possible alternative      
explanations for problems with the MOD switches, and argue that a 30-year 

service life is only possible with proper maintenance and operation.      
Bittner’s alleged failure to connect maintenance and operation issues to the 
malfunctioning of the MOD switches may be explored on cross-examination   
and goes to the weight and credibility of his testimony rather than its   
admissibility.                                                            

     C. Plaintiffs’ Motion to Exclude Certain Testimony of              
        William Coleman (ECF No. 207)                                   

   Plaintiffs seek to exclude certain testimony from William Coleman, a 
metallurgist, regarding Defendants’ conduct and thought process in        
choosing 410 stainless steel for the project, alleging that these opinions 
have no reliable factual basis. Defendants offer Coleman’s testimony to   
rebut that of Plaintiffs’ expert John C. Lippold, who opined that 410     
stainless was an inappropriate material selection for the DREs. See ECF   
No. 207-2. Plaintiffs take issue with Coleman’s “assertions about how     

TAES chose 410 stainless and handled the material, and his related        
opinions that TAES’s thinking and actions were proper.”                   
   Plaintiff contends that Coleman’s opinion about how TAES selected    

and handled 410 stainless is not reliable because he based it upon phone  
calls with Toshiba employees Scott Torvik and Takeshi Hyuga, he did not   
conduct an independent investigation, and he merely “parrots” Defendants’ 
factual account. However, both Torvik and Hyuga were involved in and      

have historical knowledge of the overhaul project. ECF No. 225-3 at 305-  
307; ECF No. 225-4 at 14-20. Although Plaintiffs argue that their         
knowledge was not firsthand and was insufficient, it is not clear that in this 
regard Coleman’s opinion veers into the territory of inadmissible         
“assumptions” or “guesses.” See In re Scrap Metal, 527 F.3d at 530.       

These “weaknesses in the factual basis of an expert witness' opinion ...  
bear on the weight of the evidence rather than on its admissibility.” Id. 
Plaintiffs may challenge the foundation and factual bases of Coleman’s    

opinions at trial, where the court is able to assess the evidence in its proper 
context. See In re E.I. du Pont de Nemours & Co. C-8 Pers. Inj. Litig., 348 
F. Supp. 3d 698, 721 (S.D. Ohio 2016) (explaining that unless evidence is 
“clearly inadmissible,” “evidentiary rulings should be deferred until trial so 

that questions of foundation relevancy and potential prejudice may be     
resolved in proper context”).                                             
     D. Plaintiff’s Motion to Exclude Certain Testimony of              
        William D. Marscher (ECF No. 208)                               

   Plaintiffs seek to exclude certain opinions of Defendants’ expert    
William D. Marscher regarding Toshiba’s “jacking up” proposal. Marscher is 
an engineer who reviewed data produced in discovery and conducted a site  
visit at the Ludington plant. ECF No. 208-7 at PageID.12593. He reviewed  
Defendants’ jacking up repair proposal and deemed it “appropriate, and    

according to best industry practice. In particular, in my opinion, the    
approach of jacking up each Unit only 400mm, rather than removal of the   
rotor, to gain access for any DR or DRE remediation is an excellent       
strategy, and quite practical.” ECF No. 208-7 at PageID.12682. Marscher   
also issued a supplemental report on the issue, in response to a          

supplemental report from Plaintiffs’ expert Marcus Crahan.                
   Marscher has fifty-four years of experience as a machinery engineer. 
ECF No. 208-7. In formulating his opinions for this case, Marscher        

reviewed the project documents, interviewed TAES employees, and           
conducted a site visit and testing at the Ludington plant. Plaintiffs challenge 
Marscher’s opinions regarding the feasibility of the jacking up proposal, 
asserting that Marscher only had one day to review the plan before        

submitting his report and that his opinion lacks a reliable factual basis and 
is conclusory. However, Marscher explained his opinion regarding why      
repair of the DREs was preferable to replacement, which “would introduce  

additional heat and distortion back into the existing embedded structures 
and introduce additional residual stress.” ECF No. 208-7 at PageID.12587- 
88. Moreover, Marscher’s specialized engineering knowledge and            
experience provide a sufficiently reliable basis for his opinions. To the 

extent Plaintiffs claim that the factual basis of Marscher’s opinion is   
incorrect or insufficient, such a challenge addresses credibility and weight 
rather than admissibility. In re Scrap Metal, 527 F.3d at 530.            
     E. Plaintiff’s Motion to Exclude Certain Testimony of              
        Jamie Petty-Galis (ECF No. 209)                                 
   Plaintiffs seek to exclude certain testimony from Defendants’ expert 
Jamie Petty-Galis, an engineer with thirty years of experience in forensic 

metallurgical and mechanical engineering consultation. Ms. Petty-Galis was 
retained to rebut the expert report of Plaintiffs’ expert, Dr. Tucker, who is a 
professional engineer with a Ph.D. in Materials Science and Engineering   

from Carnegie Mellon University. Dr. Tucker investigated the damage to the 
DRs and DREs by visiting the Ludington Plant, taking measurements, and    
analyzing high-resolution images. Dr. Tucker’s opinions are set forth in a 
425-page report, in which he concluded that damage to the DRs in Units 2  

and 4 was the result of cavitation erosion and that cracks and “crack-like 
defects” in the DREs should be repaired under the relevant engineering    
code.                                                                     

   Petty-Galis conducted a “desktop review” of Dr. Tucker’s report.     
Plaintiffs take issue with Petty-Galis’s testimony that Dr. Tucker did not 
follow the “scientific method” and that his opinion is unreliable. According to 
Petty-Galis, the only “scientific” method to determine the cause of the   

damage to the DRs and DREs is to cut out the metal and analyze it in a    
laboratory. Plaintiffs argue that Petty-Galis’s method is not the only    
“scientific” method. Petty-Galis also faults Dr. Tucker to failing to consider 
“damage tolerance methodology” and whether the cracks have reached a      
“critical size,” such that they will extend all the way through the material. 

Plaintiffs contend that whether the cracks have reached a “critical size” is 
not relevant to Dr. Tucker’s opinion that they need to be repaired.       
   Plaintiffs essentially highlight a difference of opinion with respect to 

the appropriate methodology and which factors the experts should properly 
consider. This disagreement may be explored on cross-examination. This    
type of critique does not “fall outside the range where experts might     
reasonably differ” and goes to the weight of the testimony, to be evaluated 

by the jury. See Kumho, 526 U.S. at 153; In re Heparin Prods. Liab. Litig., 
803 F. Supp. 2d 712, 753 (N.D. Ohio 2011), aff’d sub nom. Rodrigues v.    
Baxter Healthcare Corp., 567 F. App’x 359 (6th Cir. 2014) (noting that    

experts’ “critiques of each others’ methods are helpful to the jury, which 
must determine the weight to accord each expert’s testimony”).            
   Plaintiffs further object to Petty-Galis’s testimony that cavitation 
erosion in hydroelectric plants is “normal,” “natural,” and “does not imply 

poor design.” ECF No. 209-3 at PageID.12925. Plaintiffs contend that      
Petty-Galis has no basis for these opinions, which are contradicted by the 
literature upon which she relies. Defendants point out that Plaintiffs’ expert 

agrees that cavitation erosion is a common phenomenon in hydroelectric    
plants. The parties’ disagreement appears to involve whether and how      
design may impact the development of cavitation. To the extent Plaintiffs 

argue that the factual basis of Petty-Galis’s opinion in this regard is   
insufficient, “[v]igorous cross-examination [and] presentation of contrary 
evidence” is the remedy, rather than exclusion. Daubert, 509 U.S. at 596. 

   Plaintiffs also object that Petty-Galis lacks the requisite knowledge or 
experience to opine regarding the terms that are “typically” included in  
hydropower industry contracts. See ECF No. 209-3 at PageID.12926          
(opining that “[a] cavitation guarantee is typically part of the design   

specification agreements” and is a “common contractual agreement          
between purchasers and suppliers of hydropower systems.”). Defendants     
respond that Dr. Tucker “opened the door” to this testimony by putting the 

parties’ contractual terms and industry expectations at issue. They also  
point out that Petty-Galis testified that “she has evaluated numerous     
components for cavitation erosion over her 30-year career, including in   
hydroelectric systems.” ECF No. 221 at PageID 22229.                      

   Neither the alleged “opening of the door” nor her experience         
evaluating cavitation erosion addresses Petty-Galis’s foundation for opining 
what is “typical” in hydropower industry contracts. In this regard, Plaintiffs’ 

objection is well-taken. See Builders Mut. Ins. Co. v. GCC Constr., LLC,  
711 F. Supp. 3d 899, 922 (E.D. Tenn. 2024) (“Because Willingham does not  
possess specialized knowledge regarding insurance policies, he cannot     

opine as to the insurance policy at issue or the customs or practices of the 
industry.”). Provisionally, the court finds that Defendants have not      
demonstrated that Ms. Petty-Galis possesses the specialized knowledge or  

experience necessary to opine regarding industry customs with respect to  
cavitation guarantees.                                                    
     F. Plaintiffs’ Motion to Exclude Certain Testimony of              
        Richard A. Polich (ECF No. 212)                                 

   Plaintiffs seek to exclude certain opinions of Defendants’ expert    
Richard A. Polich regarding (1) Plaintiffs’ motives in rejecting Defendants’ 
“jacking up” repair; (2) how the Michigan Public Service Commission would 
rule upon or react to Plaintiffs’ repair plan; and (3) how potential repair 
plans would impact rates paid by customers. Polich is an engineer who was 

retained to rebut the report of Plaintiffs’ expert Dr. Brian M. McDonald, who 
opined on the reasonableness of Plaintiffs’ repair plan. See ECF No. 212-2. 
   Plaintiffs take issue with the following from Polich’s report: “The  
Defendants have a workable plan for repairing the Unit 2 and 4 DR/DRE     

. . . . The only reason for the Plaintiffs to choose replacement of the   
DR/DRE over repair is due to Plaintiffs’ own risk aversion, their desire to 
operate Ludington according to their generation plans, or out of a desire to 
have brand new components installed at Toshiba’s expense.” ECF No. 212-   
2 at ¶ 98. Plaintiffs argue that Polich impermissibly speculates regarding 

their motivation in rejecting Defendants’ repair plan. See In re Rezulin  
Prods. Liab. Litig., 309 F. Supp. 2d 531, 546 (S.D.N.Y. 2004) (explaining 
that experts may not offer opinions on the “intent, motives or states of mind 

of corporations, regulatory agencies and others” because these opinions   
“have no basis in any relevant body of knowledge or expertise”). Although 
Defendants suggest that Polich is not attempting to engage in “corporate  
mind-reading,” Polich admitted as much in his deposition. ECF No. 212-3 at 

159 (“I admit I’m trying to put my head in the mind of the owners.”). And 
although Defendants argue that Polich is merely rebutting Dr. McDonald’s  
report, McDonald does not opine on Plaintiffs’ specific motivations in    

rejecting Defendants repair plan, but he provides general background that 
the utility industry “has been steadily evolving towards lower overall risk 
tolerance and has a relatively low risk tolerance compared to other       
industries.” ECF No. 220-2 at ¶ 29. Polich may rebut Dr. McDonald’s view  

about the utility industry’s risk tolerance in general, but he may not    
speculate about Plaintiffs’ actual motivations. See Waite, Schneider,     
Bayless & Chesley Co., L.P.A. v. Davis, 253 F. Supp. 3d 997, 1013 (S.D.   

Ohio 2015) (“Expert testimony as to intent, motive, or state of mind offers 
no more than the drawing of an inference from the facts of the case,” which 
is “within the competence of the jury.”) (citations omitted).             

   Similarly, Plaintiffs argue that Polich may not predict how the      
Michigan Public Service Commission would view its repair plan. In his     
report, Polich states that “[i]f the Plaintiffs’ solution were presented before 

the MPSC, I think it is unlikely the costs would considered prudent or as 
meeting best utility practice thresholds.” ECF No. 212-2 at ¶ 166. In his 
deposition, he admitted attempting to predict what the MPSC “might or     
might not do,” but ultimately “I have no idea what they would do.” ECF No. 

212-3 at 304-305. Polich’s view on how the MPSC “might” receive Plaintiffs’ 
repair plan borders on speculation and will not assist the jury.          
   Plaintiffs also argue that Polich should not be able to testify regarding 

how potential repair plans may impact rates paid by customers, which are  
set by the MPSC. Defendants contend that Polich should be allowed to      
rebut McDonald’s opinion that the repair plans should be assessed         
“considering requirements for high reliability and maintaining low cost of 

services.” ECF No. 220-2 at ¶ 29. Polich opines that the Utilities’       
“preference for replacement of the Unit 2 and 4 DR/DRE is not a prudent   
utility decision nor is it good utility practice because of the potential cost 

impact on ratepayers.” ECF No. 212-2 at ¶ 96. Plaintiffs argue that Polich’s 
attempt to predict the impact of the repairs on rates does not have a     
reliable basis, but Defendants point out that Polich has “experience in rate 

design and the impact of costs on rates.” See id. at PageID.16170-74.     
The extent to which Polich’s testimony is rebuttal and whether it has a   
reliable basis is more appropriately assessed in the context of the evidence 

at trial. In addition, this issue is the subject of a motion in limine filed by 
Defendants and may become moot or substantially resolved. See ECF No.     
258.                                                                      
     G. Plaintiffs’ Motion to Exclude Certain Opinions of               
        Dakus Gunn (ECF No. 213)                                        

   Plaintiffs seek to exclude certain testimony from Defendants’        
damages expert, Dakus Gunn, in particular opinions that Plaintiffs        
characterize as legal or related to contract interpretation. First, Plaintiffs 
challenge Gunn’s opinion that certain costs should not be included in     

Plaintiffs’ damages calculation because the “plain language” of the contract 
contemplated a “major disassembly/reassembly” every ten years. ECF No.    
213-2 at ¶ 38. “A ‘major disassembly/reassembly’ of each Unit will therefore 
be due and should have always been anticipated by the Owners by the       

time Voith starts work.” Id. (emphasis in original). The parties disagree 
about the meaning of “major disassembly/reassembly,” and which costs      
Plaintiffs should have reasonably anticipated as “maintenance.” Plaintiffs’ 
position is that the need to completely dissemble units to undertake repairs 
goes beyond normal maintenance, and they instructed their expert, Michael 

Emmert, to include the cost of dismantling entire units in his damages    
calculation. Defendants’ position is that this cost would have been incurred 
in any event, as normal maintenance.                                      

   Plaintiffs argue that Gunn’s opinion that “major disassembly         
/reassembly” refers to entire units, rather than components of units, is a 
matter of contract interpretation and is inappropriate for expert testimony. 
Defendants respond that Gunn is merely rebutting Emmert’s report and is   

not providing a legal interpretation of the contract. However, Emmert     
included the costs of disassembling the units in his damages calculation  
based upon instruction from the Plaintiffs, not his interpretation of the 

contract. In contrast, Gunn appears to provide his own interpretation of the 
contract and calculate damages accordingly. ECF No. 213-3 at ¶ 175        
(“[Gunn] is of the opinion that according to the Technical Requirements, the 
Owners were going to be required to perform a major                       

disassembly/reassembly at 9-10 years of operation. . . . This would have  
necessitated the disassembly and reassembly of the units and as such [I   
am] of the opinion that these costs    . . . should be removed.”). Generally, 

contract interpretation is not a proper subject of expert testimony. See  
Consol. Rail Corp. v. Grand Trunk W. R. Co., 2011 WL 6004275, at *5 (E.D. 
Mich. Dec. 1, 2011) (“[E]xpert testimony to interpret contract language is 

inadmissible unless there is a need to interpret an ambiguity or clarify or 
define terms of art, science or trade.”) (citing N. Am. Specialty Ins. Co. v. 
Myers, 111 F.3d 1273, 1281 (6th Cir.1997); TCP Indus., Inc. v. Uniroyal,  

Inc., 661 F.2d 542, 549 (6th Cir.1981)). Although Gunn’s damages          
calculation may reflect Defendants’ legal position that certain costs should 
not be included under the contract, he may not offer his opinion about what 
the “plain language” of the contract provides or what “major              

disassembly/reassembly” means.                                            
   Plaintiffs next argue that Gunn also impermissibly opines on the     
standard of proof Plaintiffs must meet to support their damages claim.    

However, rather than rendering a legal opinion, Gunn challenges the       
factual basis for Plaintiffs’ damages calculation. See ECF No. 213-2 at ¶ 53 
(“Ankura has not provided or referenced any source documentation that is  
typically provided to substantiate a Time and Materials claim such as     

signed time sheets, material purchase orders, equipment rental invoices,  
etc.”); ECF No. 213-3 at ¶¶ 26, 30 (“There remains a substantial amount of 
missing information and support that Delta believes would be customary for 

the Owners to produce in such a dispute to validate and verify its        
damages.”). To the extent Plaintiffs believe that Gunn’s opinions in this 
regard are incorrect, they may cross-examine him and present contrary     

evidence through their expert. Daubert, 509 U.S. at 596.                  
   The parties’ next disagreement involves whether Plaintiffs’ damages  
should be discounted to net present value. Gunn’s opinion is that they    

should be, in contrast to Emmert. See ECF No. 213-3 at ¶ 38 (“[Emmert]    
has failed to consider the requirement for these future economic damages  
to be adjusted to present value. To say this principle is common          
understates its virtually ubiquitous application throughout commercial    

litigation.”). Plaintiffs argue that Gunn should confine his opinion to   
economics and not testify about the alleged “ubiquitous application       
throughout commercial litigation.” Id. However, Gunn’s deposition makes   

clear that his opinion is based upon economic principles, not litigation  
norms. ECF No. 222-2 at 202-208 (“It’s the time value of money.”). To the 
extent Gunn strays beyond his expertise, Plaintiffs may raise such        
challenges at trial.                                                      

     H. Defendants’ Motion to Exclude Certain Testimony of              
        Marcus Crahan (ECF No. 214)                                     

   Defendants seek to exclude certain testimony from Plaintiffs’ expert 
Marcus Crahan. Crahan is a professional engineer with more than thirty    
years of experience as an engineering consultant specializing in the failure 
analysis and performance testing of large rotating machinery, particularly in 
the hydroelectric industry. Crahan opined that TAES should have placed    

the lower wear ring seal (also known as annular seal) at the bottom of the 
runner, rather than above the bottom of the runner. He relied in part on a 
paper written in 1965 by Toshiba engineers Hisao Tomita and Mitsuo        

Kawamura, which appeared in the Toshiba Review (the “Tomita paper”).      
According to Crahan, TAES deviated from a design principle, first         
established by the Tomita paper, that the lower annular seal should be    
located “at the very bottom of the runner”; when the seal is located above 

the bottom of the runner, the result is abnormal shaft vibration. Units 2 and 
4 at the Ludington Plant experienced abnormal shaft vibration, which      
Crahan opines was the result of the location of the seal.                 

   Defendants argue that the Tomita paper does not state that the seal  
must be placed at the bottom of the runner, as opposed to elsewhere. But  
Crahan explained in his report and deposition why he believes a design    
principle flows from Tomita’s work. See ECF No. 214-2 at PageID.16764-    

65; ECF No. 223-2 at 86-87, 91-99 (“Mr. Tomita is opining that if you want 
to have a stable rotordynamic Francis turbine of medium or moderate       
specific speed, you want the annular seal at the bottom of the runner     

band.”). Crahan’s interpretation of the Tomita paper, which is informed by 
his knowledge and experience, does not appear to be so unsupported as to  
be unreliable. Cf. In re Onglyza (Saxagliptin) & Kombiglyze (Saxagliptin & 

Metformin) Prods. Liab. Litig., 93 F.4th 339, 346 (6th Cir. 2024) (affirming 
exclusion of medical causation expert who relied upon one study to opine  
that the drug caused heart failure, a connection not made in the study).  

Indeed, Toshiba engineers co-wrote a paper regarding shaft vibration at the 
Ludington Plant that recognized that “[t]he outlet seal of new runner was 
not located at the bottom of the runner band . . . in case of which the   
upstream seal clearance is narrower than the downstream seal clearance,   

generally known as a cause of self-excited vibration.” ECF No. 223-4 at   
PageID.23905. For this proposition, the paper cited the Tomita paper. Id. at 
PageID.23918. Defendants’ expert also acknowledged that normally the      

wear ring is designed to be “right at the end” of the runner. ECF No. 223-3 
at 223-28. To the extent Defendants disagree with Crahan’s interpretation 
of the Tomita paper, they may highlight that difference through cross-    
examination and the presentation of contrary evidence.                    

   Defendants also seek to exclude Crahan’s opinion that the placement  
of the wear ring seal caused “foreseeable self-excited vibrations and     
cavitation erosion of the discharge ring,” arguing that Crahan did not test 

this theory. However, under the circumstances of this case it is not fatal that 
Crahan did not conduct his own tests. “[A]n expert need not actively      
conduct his or her own tests to have a valid methodology”: “either ‘hands 

on testing’ or ‘review of experimental, statistical, or other scientific data 
generated by others in the field’ may suffice as a reasonable methodology 
upon which to base an opinion.” Buck v. Ford Motor Co., 810 F. Supp. 2d   

815, 844 (N.D. Ohio 2011) (citing Clark v. Takata Corp., 192 F.3d 750, 758 
(7th Cir.1999)); cf. Johnson v. Manitowoc Boom Trucks, Inc., 484 F.3d 426, 
431 (6th Cir. 2007) (excluding expert who proposed an alternative,        
allegedly safer design in product liability case without testing it).     

   Crahan relied on evidence in the record to support his conclusions   
regarding vibration, including a paper published by Toshiba regarding the 
Ludington plant. The paper “takes the reader through, step by step, the   

finding of the self-excited vibration, the testing that was done both at the 
site and back in Japan at the model lab to verify that, in fact, the Tomita 
effect is the root cause of the self-excited vibration at -- at Ludington.” ECF 
No. 223-2 at 126-27. As for his opinion regarding cavitation, Crahan      

supports it with engineering calculations (“the Brennen equation”) and his 
analysis of hydrodynamic testing of a model of the Ludington units that was 
done in a laboratory in 2010. ECF No. 214-2 at PageID.16774-79. Although  

Defendants disagree with Crahan’s conclusions, they have not              
demonstrated that Crahan’s approach is unreliable under the               
circumstances.                                                            

     I.  Defendants’ Motion to Exclude Certain Testimony of             
        Sara T. Walz (ECF No. 215)                                      

   Defendants object to the testimony of Plaintiffs’ expert Sara T. Walz, 
arguing that her opinions are not relevant or reliable and that she lacks the 
necessary qualifications. Walz has prepared models estimating the cost    
impact to Consumers if the Ludington Pumped Storage Plant is unable to    
generate electricity. She is the Director of Electric Supply Planning for 
Consumers Energy; her background includers a bachelor’s degree in         
mathematics from Michigan State University and a master’s degree in       

applied mathematics, where she focused in mathematical modeling.          
   Walz provides an opinion regarding the value of the Ludington plant’s 
capacity and energy generation, and the loss of value Plaintiffs could    

expect to incur if the plant is taken offline for repairs. Walz prepared these 
calculations using mathematical models that she employs in the ordinary   
course of her work at Consumers. ECF No. 215-2 at 1. She calculated the   
daily value of the Ludington plant in terms of capacity and energy        

production, then assumed certain outage periods, given information        
supplied by other Consumers employees. In Scenario 1, Walz assumes        
that Units 2 and 4 are offline for 600 days, which is the length of time that it 
is estimated the Voith Hydro repair will take. This outage results in an  
estimated capacity loss of $145.8 million. In Scenarios 2A and 2B, Walz   

assumes longer, more expensive outages based upon the need to             
undertake future, unplanned repairs. Walz also estimates the costs of     
replacing the two units with a similar battery storage facility.          

   Defendants challenge the admissibility of Walz’s testimony on several 
grounds. First, they argue that her estimates are not relevant, as they are 
not used as a basis for Plaintiffs’ damages calculation. (According to    
Defendants, the contract excludes losses incurred as a result of a plant  

shutdown.) Plaintiffs counter that the bar for relevancy is “low,” and that 
Walz’s testimony will provide context and otherwise assist the trier of fact to 
understand issues in the case. See LaVictor, 848 F.3d 428 at 442          

(explaining that to be relevant, the testimony must “logically advance[] a 
material aspect of the proposing party’s case”). For example, Plaintiffs  
contend that Walz’s testimony will help illustrate the risks of Toshiba’s 
approach to operate with defective components “as is” and “wait and see” if 

problems develop, and to rebut Defendants’ argument that the costs of     
repairs undertaken by Plaintiffs outweigh the benefits. Plaintiffs also assert 
that Walz’s calculations support their decision to reject Defendants’ “jacking 

up” repair proposal, which they believe creates the risk of an extended   
outage. At this stage, it appears that Walz’s testimony meets the relatively 
low relevancy threshold.                                                  

   Defendants next argue that Walz’s testimony is unreliable because it 
is based upon assumptions with no factual support in the record. They     
challenge Walz’s assumptions that Units 2 and 4 will fail within the next few 

years and that this failure will result in outages spanning three to six years. 
These assumptions, which Walz did not independently validate, were        
provided by other Consumers employees. Plaintiff responds that support    
for Walz’s assumptions will be adduced at trial, including testimony from 

Kristopher Koster, the principal project manager for the Ludington Plant  
repair, who will testify regarding the outage timing and duration for the Voith 
Hydro repair and the lead time necessary to plan for a repair outage.     

Plaintiffs also note that Units 2 and 4 are presently restricted in their 
operation. In this regard, there is “some support” for Walz’s assumptions in 
the record; an ultimate assessment of whether Walz’s assumptions are      
supported by the evidence is more appropriately undertaken at trial. See  

Davis v. Sig Sauer, Inc., 126 F.4th 1213, 1224 (6th Cir. 2025) (“An expert's 
opinion, where based on assumed facts, must find some support for those   
assumptions in the record.”) (citation omitted).                          
   Defendants also challenge Walz’s qualifications, arguing that she    
may not opine on technical issues because she is not an engineer. It does 

not appear, however, that Walz offers opinions requiring engineering      
knowledge, as she does not predict whether outages will occur, but        
assumes that they will occur and then uses her expertise to calculate the 

cost. Defendants further argue that Walz’s experience with modeling is    
“limited,” and that she has not published articles, taught courses, subjected 
her work to peer review, or served as an expert in other cases. However,  
Walz has a master’s degree in applied mathematics with a focus in         

mathematical modeling. For seventeen years, she has engaged in            
mathematical modeling as part of her work for Consumers and Consumers     
relies upon her modeling in the normal course of its business. In this    

regard, her education and experience are sufficient; she is not required to 
be a professor or professional litigation expert to be qualified. See Bradley 
v. Ameristep, Inc., 800 F.3d 205, 208-209 (6th Cir. 2015) (noting that the 
court takes “a liberal view of what ‘knowledge, skill, experience, training, or 

education’ is sufficient”).                                               
     J.  Defendants’ Motion to Exclude Certain Opinions of              
        Joseph C. Tucker (ECF No. 216)                                  

   Defendants seek to exclude certain opinions of Dr. Joseph Tucker     
that “impermissibly parrot” and bolster that of Plaintiffs’ other experts with 
respect to “DR damage” and “DRE indications.” With respect to these       
issues, Defendants argue, Dr. Tucker relied upon the opinions of Dr.      

Zachary Owens and Dr. Brian McDonald “rather than conducting any          
independent scientific evaluation of his own.” ECF No. 216 at             
PageID.19637.                                                             

   Although experts “may rely on the opinions and conclusions of other  
experts when forming their own independent conclusions throughout their   
own independent investigation,” they may not “simply ‘parrot,’ ‘echo,’    
‘regurgitate,’ or ‘bootstrap’ the opinion or conclusion of another expert 

without any independent evaluation or analysis.” Saginaw Chippewa Indian  
Tribe of Michigan v. Blue Cross Blue Shield of Michigan, 745 F. Supp.3d   
524, 534 (E.D. Mich. 2024) (citing cases).                                

   Dr. Tucker is a licensed professional engineer with degrees in       
materials science and engineering, including a Ph.D. from Carnegie Mellon 
University. He investigated the damage of the DR/DREs at the Ludington    
plant in person, spending at least 25 days at the plant gathering data,   

including taking photos with a borescope (a tiny camera on a flexible tube) 
and obtaining measurements of material loss. See ECF No. 216-2 at         
PageID.19667-68, 19900-923. He also considered the history and            
operation of the plant, as well as the scientific literature, in reaching his 
opinions. See ECF No. 227-3.                                              

   Among other conclusions, Dr. Tucker opined that damage to the DRs    
in Units 2 and 4 was the result of cavitation erosion. ECF No. 216-2 at   
PageID.19757. His report described his “observations regarding the DR     

damage and my opinion that this damage is consistent with cavitation      
erosion, not galvanic corrosion.” Id. He also stated that “[o]bservations of 
the damage are consistent with the results of CFD [computational fluid    
dynamic] simulations in Section 5 of Dr. Owens’s report which predict     

cavitation erosion as the primary damage mechanism.” Id.                  
   Contrary to Defendants’ argument, it is clear from Dr. Tucker’s report 
and deposition that he conducted his own investigation and analysis and   

did not merely adopt Dr. Owen’s opinion wholesale. See ECF Nos. 227-2 at  
23-31. His partial reliance on Dr. Owens’s findings is not impermissible. 
See, e.g., Modern Holdings, LLC v. Corning, Inc., 2022 WL 2910005, at *6  
(E.D. Ky. July 22, 2022) (“While it is true that one expert may not simply 

‘adopt another expert’s opinions wholesale,’ it is firmly established under 
Rule 703 that an expert’s testimony may be formed using the conclusions   
and opinions of other experts.”) (citation omitted; collecting cases). To the 

extent Defendants identify other alleged flaws in Dr. Tucker’s investigation 
or analysis – that he did not conduct laboratory testing or that he “cherry-
picked” photos – that is grist for cross-examination, not exclusion.      

   Defendants also challenge Dr. Tucker’s opinion that cracks and       
crack-like flaws or “indications” in the DREs create the risk of structural 
failure. In particular, Defendants contend that Dr. Tucker is merely      

regurgitating Dr. McDonald’s opinion. ECF No. 216-2 at 129 (“As discussed 
in Section 5.1 of Dr. McDonald’s report, this can create considerable risk 
and uncertainty regarding structural condition of the DRE and may even    
compromise achieving the CCS-specified service life of at least 30 years.”). 

   Plaintiffs respond that Dr. Tucker conducted his own investigation of 
the alleged defects in the DREs, including analyzing liquid penetrant or “PT 
testing.” They contend that PT testing is a “well-accepted” method to     

identify cracks and other flaw in metal components. When flaws are        
identified using PT testing, engineering codes provide criteria to determine 
whether a flaw should be repaired based upon its size and shape. Dr.      
Tucker also took photographs of the flaws and analyzed the images with    

reference to the relevant engineering code (BPVC), performed field tests of 
the DRE metal, and conducted laboratory testing of an exemplar DRE that   
had cracked beyond repair. ECF No. 227-2 at 204-209; ECF No. 216-2 at     
PageID.19970-20065. Defendants’ argument that Dr. Tucker relies solely    
on Dr. McDonald’s report is unavailing. See ECF No. 227-2 at 240-47.      

   Defendants argue that because Dr. Tucker did not measure the depth   
of the cracks or find them to be of “critical” size, he has no basis to opine 
regarding structural integrity or whether the cracks should be repaired.  

Plaintiffs assert that whether the cracks are “critical” is not relevant to Dr. 
Tucker’s opinion that the cracks meet BPVC criteria and should be repaired 
or a fitness-for-service (“FFS”) analysis performed. Dr. Tucker further   
opines that, for various reasons, an FFS analysis may not be reliably     

performed under the circumstances, the defects continue to grow, and thus 
frequent monitoring is necessary to address the “risk and uncertainty,”   
including the risk of failure. Dr. Tucker’s opinion rests upon sufficiently 

reliable grounds; to the extent there are matters or data that Dr. Tucker 
failed to consider, they go to weight and credibility rather than admissibility. 
III.  Conclusion                                                        
   It is ORDERED as follows: 1) Plaintiffs’ Motion to Exclude Certain   

Opinions of Bernhard Bittner (ECF No. 206) is DENIED WITHOUT              
PREJUDICE; 2) Plaintiffs’ Motion to Exclude Certain Testimony of William  
Coleman (ECF No. 207) is DENIED WITHOUT PREJUDICE; 3) Plaintiffs’         

Motion to Exclude Certain Testimony of William D. Marscher (ECF No. 208)  
is DENIED WITHOUT PREJUDICE; 4) Plaintiffs’ Motion to Exclude Certain     
Testimony of Jamie Petty-Galis (ECF No. 209) is GRANTED IN PART AND       

DENIED IN PART, WITHOUT PREJUDICE; 5) Plaintiffs’ Motion to Exclude       
Certain Testimony of Richard A. Polich (ECF No. 212) is GRANTED IN        
PART AND DENIED IN PART, WITHOUT PREJUDICE; 6) Plaintiffs’ Motion         

to Exclude Certain Testimony of Dakus Gunn (ECF No. 213) is GRANTED       
IN PART AND DENIED IN PART, WITHOUT PREJUDICE; 7) Defendants’             
Motion to Exclude Certain Testimony of Marcus Crahan (ECF No. 214) is     
DENIED WITHOUT PREJUDICE; 8) Defendants’ Motion to Exclude                

Testimony of Sara T. Walz (ECF No. 215) is DENIED WITHOUT                 
PREJUDICE, and 9) Defendants’ Motion to Exclude Certain Testimony of      
Joseph C. Tucker (ECF No. 216) is DENIED WITHOUT PREJUDICE.               

   SO ORDERED.                                                          
Dated: September 26, 2025               s/F. Kay Behm                     
                                      F. Kay Behm                       
                                      United States District Judge