Document Category: Substance Use

This motion argues that evidence of a client’s alleged substance use must be excluded because it constitutes impermissible character evidence under FRE 404(a), poses a high risk of unfair prejudice under FRE 403, and invites unqualified medical opinion testimony in violation of FRE 701. Citing social-science research showing that jurors associate substance use with immorality, violence, and dishonesty, the motion argues that such evidence leads jurors to condemn defendants based on stigma rather than proof of guilt, rendering the evidence unfairly prejudicial. Finally, it explains that terms such as “addict,” “dependence,” and “abuse” describe medical diagnoses that only qualified experts may offer, rendering lay testimony about addiction inadmissible.

This brief argues that, contrary to stereotypes, drug use alone—even frequent or illicit use—does not necessarily indicate substance abuse (pp. 23, 28-29). Only a minority of users develop a diagnosable SUD (p. 23). A single positive drug test is insufficient to establish a SUD (p. 29). And equating substance use, even a SUD, with substantial risk of harm to a child is unsupported by the medical evidence (pp. 40-42).  Defenders can use the research collected in this brief to file motions in limine to exclude evidence of or arguments about substance use as more prejudicial than probative or to obtain expert testimony on substance use.  The research could also be useful at the pretrial release and sentencing stages to suggest that clients do not suffer from a substance abuse disorder and do not pose a danger.