Motion in Limine to Exclude Evidence of 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.