What does Rule 404(a) generally prohibit?

What does Rule 404(a) generally prohibit?

• A. Using evidence of a defendant's or witness's character to prove that they acted in accordance with that character on a particular occasion.
• B. Admitting lay opinions.
• C. Admitting expert testimony about ultimate issues.
• D. Admitting habit evidence to show conduct.

Answer: (C)

Rule 404(a) bars using evidence of a person’s character to prove that they acted in accordance with that character on a particular occasion. This is the rule’s core aim: prevent propensity reasoning so a jury doesn’t convict or believe something based on who the person is in general rather than what happened in the case. The option describing using character to show conduct on a specific occasion fits this prohibition exactly, making it the best answer. The other options point to different rules. Lay opinions fall under general admissibility rules for testimony (not 404(a)’s focus). Admitting expert testimony about ultimate issues is governed by rules about expert testimony and ultimate issues, not the 404(a) prohibition. Habit evidence, meanwhile, is admissible under a separate rule that recognizes habitual responses to particular situations.

Rule 404(a) bars using evidence of a person’s character to prove that they acted in accordance with that character on a particular occasion. This is the rule’s core aim: prevent propensity reasoning so a jury doesn’t convict or believe something based on who the person is in general rather than what happened in the case. The option describing using character to show conduct on a specific occasion fits this prohibition exactly, making it the best answer.

The other options point to different rules. Lay opinions fall under general admissibility rules for testimony (not 404(a)’s focus). Admitting expert testimony about ultimate issues is governed by rules about expert testimony and ultimate issues, not the 404(a) prohibition. Habit evidence, meanwhile, is admissible under a separate rule that recognizes habitual responses to particular situations.