Federal Rule of Evidence 407 prohibits plaintiffs from introducing evidence of subsequent remedial measures to show that the defendant is to blame. Among its purported justifications, the rule prevents hindsight bias from unduly influencing jury decisions. Nonetheless, plaintiffs often take advantage of the rule’s numerous exceptions to introduce evidence of remedial measures for other purposes (e.g. to prove feasibility). Fearing that the exceptions could swallow the rule, some courts will even exclude evidence that fits into one of these exceptions because it is ostensibly too prejudicial. Alternatively, other courts instruct juries that they should only use the evidence for the limited permissible purpose, but not for proving blameworthiness. This complex scheme makes several assumptions about how evidence of remedial measures and the accompanying limiting instructions influence juries. Although many studies have examined hindsight bias in other contexts, and one older study looked at Rule 407 in particular, these studies typically used short, written vignettes with small sample sizes. Moreover, none of these studies examined how subsequent measures impact damages. We sought to test these concepts in robust fashion by conducting two separate experiments using videos that included rich fact patterns including arguments from both parties and jury instructions. In the end, over one thousand seven hundred mock jurors rendered verdicts on liability, contributory negligence, and damages. As expected, evidence of subsequent remedial measures helped plaintiffs win more often. But surprisingly, our results also suggested that taking remedial measures may lower damages, thereby counteracting the increased liability findings. We also studied the efficacy of two limiting jury instructions. In one experiment, a limiting instruction with an explanation reduced but did not eliminate the effects of evidence of subsequent remedial measures. The instruction with explanation was also consistently more effective than the simple limiting instructions, but these results were not statistically significant. We hypothesize about the potential reasons for our various results and discuss what they mean for policymakers, litigants, and future researchers that may wish to explore this subject in more depth.

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