Provisional Assumptions

In courtrooms, the law often asks individuals to ignore information—carefully, purposely—that otherwise feels important. Juries, for example, are often asked to disregard information about a variety of facts, from prior convictions to settlement negotiations. But legal literature and psychology research has shown us that it is difficult for jurors to follow these instructions and cabin their curiosity about different facts in a case. Jurors have difficulty suppressing their thoughts; they rebel against admonitions; they create story-based hypotheses that are resistant to change.

To help align these evidence exclusions with empirical realities, this Article introduces an original tool: a provisional assumption. A provisional assumption would ask jurors not to ignore information but to assume certain information about subjects for which evidence is inadmissible; for instance, to assume that a civil defendant has no insurance against liability or that a criminal defendant has no prior criminal record. Drawing from psychological theories that explain why people rebel against admonitions, such as mental control and reactance, I test provisional assumptions using two experimental studies. Leveraging the context of insurance and its inadmissibility in tort cases, the results suggest that this approach would allow jurors to focus on the facts that matter. Provisional assumptions appear to hold promise as a portable intervention applicable in boardrooms and interview suites as well as courtrooms, and as a model of procedural innovation informed by interdisciplinary research.


In July 1987, Steve Terry was playing catch with his two sons when the ball landed in a tree.[1] When Terry tried to reach for the ball with a pole, he struck an improperly installed power line and was electrocuted, causing him severe injury.[2] Four years later, a jury awarded more than $5 million to Terry, but the utility company, Plateau Electric Cooperative, moved for a mistrial.[3] Its argument: the jury had heard something forbidden.

Plateau believed that Terry’s attorney had improperly prejudiced the jurors by eliciting testimony that mentioned in passing that the utility company owned insurance,[4] and it brought affidavits from three jurors mentioning what other jurors had said: that the utility company’s “insurance carrier would not miss” $5 million,[5] that “the corporation always ‘gets over on the individual and I am not going to let it happen this time,’ ”[6] and that “sometimes ‘you just have to break the law.’ ”[7]

To the appeals court, these statements went beyond the “life experiences”[8] jurors are “encouraged . . . to rely upon”[9] into “an astonishing amount of extraneous prejudicial information.”[10] Even though it might be “common knowledge” that Plateau, as a utility company, had liability insurance,[11] to the judge on appeal, that “argument beg[ged] the question: What would the verdict have been had there been no insurance, with that fact being made known to the jury?”[12]

This Article seeks to unpack that question. Terry’s case is just one illustration of how insurance status can generate assumptions about a party’s ability to pay damages and its responsibility. But such assumptions occur across other subjects of litigation, from car accidents[13] to medical malpractice[14] to corporate indemnification.[15]

By excluding information about a party’s insurance status—or their lack thereof—federal[16] and state[17] rules of evidence, alongside their early common law underpinnings,[18] attempt to reduce bias and confusion among jurors. And in an attempt to make this exclusion effective, courts instruct jurors either to disregard insurance status if it slips out during the trial or to only regard it for a particular purpose.[19] These admonitions rest on the assumptions that jurors can disregard inadmissible information that enters the courtroom, that they can consider a piece of evidence for one purpose but not for others, and that they can prevent speculation about inadmissible information.[20]

Yet, we know these assumptions can be fictive. In other evidentiary situations in which jurors encounter admonitions from a judge, the admonition frequently fails. For instance, notwithstanding instructions to ignore information about a defendant’s criminal record, jurors are more likely to think that defendants with prior convictions are guiltier.[21] Jurors also incorporate information from the news into their deliberative processes, despite the presence of admonitions.[22] This pretrial publicity can lead to harsher treatment of criminal defendants,[23] even if jurors believe they are being unbiased.[24]

Perhaps courts could exert extra effort in “blindfolding,” ensuring that inadmissible information is not mentioned at all, by incentivizing parties to create comprehensive motions in limine that exclude evidence and sanctioning violations of the motion.[25] But even if inadmissible information were to be perfectly hidden or “blindfolded” from jurors, in actuality, jurors might use their everyday stereotypes to construct their narrative of the case, as in Terry v. Plateau Electric Cooperative.[26] They also might speculate about missing information, to the detriment of focusing on the facts at hand.[27] The problem remains: How do we prevent people from their own speculation, if telling them not to consider information—that is, an admonition—might make them more likely to do it?

In this Article, I use the evidentiary limitations on the admissibility of insurance as a springboard to help understand how we might reduce juror speculation and to offer an alternative to jury admonitions. I suggest that courts should consider providing a provisional assumption for jurors, that is, request that jurors assume a particular piece of information when making their determination. I theorize that such provisional assumptions will reduce the inadmissible information’s salience and allow individuals to focus on the facts that courts deem most important.

To investigate whether provisional assumptions could work, I use a pair of survey experiments relating to the admissibility of insurance in trials. The experiments ask mock jurors in an online study to assume that neither the plaintiff nor the defendant has insurance, comparing them to another group of mock jurors who are simply given a standard jury instruction that says generally that insurance should not be considered. I find that those jurors asked to provisionally assume no insurance are less likely to be interested in the plaintiff’s insurance and may award less damages to the plaintiff. And I find potential evidence that these results are robust under uncertainty.

By accounting for the psychology of jury decision-making, the provisional assumption intervention aligns legal theories with human psychology, while yielding several policy-relevant benefits. First, allowing jurors to assume facts about insurance allows them to concentrate on the questions that matter to the law and prevents jurors from making assumptions that might be inconsistent with those of the other jurors or the objectives of the evidentiary rule at hand. Second, a provisional assumption is a solution whose simple implementation generates minimal bias to either party. Third, this procedural innovation is behaviorally informed but does not treat jurors in a patronizing fashion. Providing jurors with a provisional assumption might displace the assumptions they have—and also displace our own assumptions about how jurors behave.

This Article proceeds in three parts. Part I lays out the historical and functional importance of the evidence rules underlying the exclusion of insurance status from jury consideration. It then addresses how courts have dealt with the exclusion in practice. Part I also shows how jury instructions fall short  of eliminating forbidden information by illustrating the disconnect between evidentiary exclusions and empirical realities via classic examples in social psychology and jury studies.

Part II contains two original studies. It imagines what an ideal intervention would look like and introduces the provisional assumption as a psychology-based intervention, consistent with legal intuitions about evidence. It then describes and reports on the results of two original survey experiments that demonstrate the first-ever use of this intervention.

Lastly, Part III explores the implications of these studies for juror decision-making and legal decision-making generally. To be sure, the frequency of civil jury trials has steadily diminished over time. Still, understanding how jurors speculate might have parallels to other situations in which the law asks people to not consider certain information. I address several potential objections to the implementation of the provisional assumption and argue that implementation of psychological innovations helps to conform the underlying rationale of the law with legal actors’ expectations.

          [1].      Terry v. Plateau Elec. Coop., 825 S.W.2d 418, 420 (Tenn. Ct. App. 1991).

          [2].      Id.

          [3].      Id. at 419, 421.

          [4].      Id. at 421.

          [5].      Id.

          [6].      Id. at 422.

          [7].      Id. at 421–22.

          [8].      Id. at 423.

          [9].      Id.

        [10].      Id. Under Rule 606 of the Federal Rules of Evidence, juror testimony may not be used to impeach a verdict unless “extraneous prejudicial information was improperly brought to the jury’s attention” or “an outside influence was improperly brought to bear on any juror.” Fed. R. Evid. 606(b); see also Warger v. Shauers, 574 U.S. 40, 48 (2014).

        [11].      Terry, 825 S.W.2d at 423.

        [12].      Id.

        [13].      See, e.g., Valerie P. Hans & Nicole Vadino, Whipped by Whiplash? The Challenges of Jury Communication in Lawsuits Involving Connective Tissue Injury, 67 Tenn. L. Rev. 569, 581 (2000); Tim A. Baker, Sizing Up Settlement: How Much Do the Merits of a Dispute Really Matter?, 24 Harv. Negot. L. Rev. 253, 257–58 (2019).

        [14].      See Lauren Gailey, “I’m Sorry” as Evidence? Why the Federal Rules of Evidence Should Include a New Specialized Relevance Rule to Protect Physicians, 82 Def. Couns. J. 172, 181 (2015).

        [15].      See Baker, supra note 13, at 257.

        [16].      See Fed. R. Evid. 411.

        [17].      See, e.g., 6 Jack B. Weinstein & Margaret A. Berger, Weinstein’s Federal Evidence art. IV (Mark S. Brodin ed., 2d ed. 1997).

        [18].      See Banks McDowell, The Collateral Source Rule—The American Medical Association and Tort Reform, 24 Washburn L.J. 205, 205 (1985).

        [19].      See Justin Sevier, Evidence Law and Empirical Psychology, in Philosophical Foundations of Evidence Law 349, 356–57 (Christian Dahlman, Alex Stein & Giovanni Tuzet eds., 2021).

        [20].      See Shari Seidman Diamond & Neil Vidmar, Jury Room Ruminations on Forbidden Topics, 87 Va. L. Rev. 1857, 1864–66 (2001); Sevier, supra note 19, at 356–58.

        [21].      See Roselle L. Wissler & Michael J. Saks, On the Inefficacy of Limiting Instructions: When Jurors Use Prior Conviction Evidence to Decide on Guilt, 9 Law & Hum. Behav. 37, 41–43 (1985); David Crump, Does Impeachment by Conviction Create Undue Prejudice? An Experiment and an Analysis, 53 Akron L. Rev. 1, 16 (2019). The effect of prior convictions on liability extends to civil contexts. See Kathryn Stanchi & Deirdre Bowen, This Is Your Sword: How Damaging Are Prior Convictions to Plaintiffs in Civil Trials?, 89 Wash. L. Rev. 901, 927–29 (2014). Although information about prior convictions might be admitted to undermine a defendant’s credibility, it also appears to increase her liability in the jury’s eyes. See Sarah Tanford & Michele Cox, The Effects of Impeachment Evidence and Limiting Instructions on Individual and Group Decision Making, 12 Law & Hum. Behav. 477, 488 (1988).

        [22].      See, e.g., Stanley Sue, Ronald E. Smith & Renee Gilbert, Biasing Effects of Pretrial Publicity on Judicial Decisions, 2 J. Crim. Just. 163, 170 (1974); Geoffrey P. Kramer, Norbert L. Kerr & John S. Carroll, Pretrial Publicity, Judicial Remedies, and Jury Bias, 14 Law & Hum. Behav. 409, 431 (1990); Gary Moran & Brian L. Cutler, The Prejudicial Impact of Pretrial Publicity, 21 J. Applied Soc. Psych. 345, 360 (1991).

        [23].      See Nancy Mehrkens Steblay, Jasmina Besirevic, Solomon M. Fulero & Belia Jimenez-Lorente, The Effects of Pretrial Publicity on Juror Verdicts: A Meta-Analytic Review, 23 Law & Hum. Behav. 219, 229 (1999); Kramer et al., supra note 22, at 431; Moran & Cutler, supra note 22, at 360.

        [24].      See Moran & Cutler, supra note 22, at 362.

        [25].      See Diamond & Vidmar, supra note 20, at 1863–64.

        [26].      Terry v. Plateau Elec. Coop, 825 S.W.2d 418, 421–23 (Tenn. Ct. App. 1991); see, e.g., Shari Seidman Diamond & Jonathan D. Casper, Blindfolding the Jury to Verdict Consequences: Damages, Experts, and the Civil Jury, 26 Law & Soc’y Rev. 513, 516 (1992); Diamond & Vidmar, supra note 20, at 1861.

        [27].      See Diamond & Vidmar, supra note 20, at 1864–65.

* Sharswood Fellow, the University of Pennsylvania Carey Law School. J.D., Harvard Law School (2017); Ph.D., Harvard University (2020). Many thanks to David Abrams, Kim Ferzan, Jill Fisch, Jonah Gelbach, Chris Hampson, David Hoffman, Jon Klick, Sandy Mayson, Serena Mayeri, Gideon Parchomovsky, Tess Wilkinson-Ryan, and Maggie Wittlin, and workshop participants at Albany, Brooklyn, Columbia, Chapman, Chicago, Duke, Florida State, Fordham, George Washington, Georgia State, Minnesota, Texas A&M and Wyoming law schools, as well as conference participants at SEALS and the Inaugural Workshop for Asian American and Pacific Islander Women in the Legal Academy, for comments and conversations.


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