Bad Habits

58 Pages Posted: 3 May 2022 Last revised: 22 Dec 2022

See all articles by Teneille R. Brown

Teneille R. Brown

University of Utah - S.J. Quinney College of Law

Date Written: January 1, 2022


Addiction is a puzzle. Depending on whom you ask, you might be told it is a physical brain disease, a response to trauma, a disability, a behavioral compulsion, a mental illness, the result of bad personal choices, or some combination of these. Addiction has defied easy classification because it straddles many binaries. It is physical and mental, behavioral and psychological, genetic and environmental, external and internal. There are aspects that involve personal choices and aspects that do not. Historically, addiction has been viewed largely as a moral failing. Only in the last few decades have advances in genetics, neuroscience, and the social determinants of health greatly complicated the story we tell about the causes of addiction--revealing many of the above binaries to be false. The more we learn, the more we realize that developing severe addiction has much less to do with moral fortitude, and much more to do with factors outside of our control.

But this paper is only peripherally about the causes of addiction. Rather, it uses addiction to expose the cracks and inconsistencies in our evidence rules. Parties in civil and criminal trials in the United States frequently seek to introduce evidence that a party has an addiction. Given how stigmatized addiction is, whether this evidence is admitted can have a huge impact on the outcome of the trial. Unfortunately, the party's success in getting this admitted depends primarily on whether the judge views addiction as 1) a character trait, 2) a psychiatric diagnosis, 3) a physical trait, or 4) a habit. And which is the correct framing, exactly? It turns out, addiction is all of these things. While it was traditionally considered quintessential character evidence, courts are warming to the idea of it being a habit, a psychiatric diagnosis, and maybe one day even ordinary physical evidence. In this article I explore how the complex causes of addiction reveal false dichotomies in our evidentiary rules, and the overlap between types of evidence that are meant to be distinct. Additionally, I will argue that the blurring together of these categories of evidence is made possible by our untethering the rules from their moral roots, as well as advances in our understanding of the causes of human behavior.

Many of the common law rules developed hundreds of years ago, when the science of human behavior was simplistic. We held exaggerated views of individual agency and ignored the powerful effects of trauma and biology. This article is part of a larger project of advocating for revisions to our rules of evidence, so that they better reflect the modern understanding of human behavior, with all of its inevitable complexity.

Keywords: evidence, addiction, character evidence, habit evidence, trials, admissibility, human behavior, psychology, causal attribution

Suggested Citation

Brown, Teneille R., Bad Habits (January 1, 2022). University of Utah College of Law Research Paper No. 497, Available at SSRN: or

Teneille R. Brown (Contact Author)

University of Utah - S.J. Quinney College of Law ( email )

383 S. University Street
Salt Lake City, UT 84112-0730
United States

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