Whether the character evidence rule -- the prohibition against circumstantial use of character -- applies in civil cases.

Fed. R. Evid. 103(a) ("(a) Effect of erroneous ruling. Error may not be predicated upon a ruling which admits or excludes evidence unless a substantial right of the party is affected, and ... (2) Offer of proof. - In case the ruling is one excluding evidence, the substance of the evidence was made known to the court by offer or was...If a trial court is unwilling to accept a general offer of evidence, the proponent of the evidence must make a specific offer of evidence.

Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579, 589-590, 592-593 (1993) ("The primary locus of this obligation is Rule 702, which clearly contemplates some degree of regulation of the subjects and theories about which an expert may testify. 'If _scientific_, technical, or other specialized...A field or method that is offered as as a scientific field or method satisfies the requirements for the admissibility of evidence under Federal Rule 702 or a comparable State rule only if the field or method is shown to be genuinely scientific.

Adams v. City of Chicago, 469 F.3d 609, 612-613 (7th Cir. 2006) (holding, in plaintiff minority police officers' disparate impact claim, that evidence of changes in promotional methods was improperly excluded under Rule 407....Although subsequent remedial measures may not be used to prove negligence, culpable conduct, a defect in the product or its design, or a need for warning or instruction, subsequent remedial measures are admissible to show the feasibility of precautionary measures.