Pily raised the following after class: Isn't "other crimes" evidence punishing someone for past actions rather than for current conduct, raising double jeopardy and due process concerns, especially if we require less evidence (proof sufficient to support a finding) to allow its use? This captures the theoretical and policy-based objection to this type of evidence. And it is a sub-species of the general objection to character evidence and why it is generally precluded--we punish bad conduct not bad people and the introduction of character evidence tempts the jury towards the latter.
The courts' answer has always been that any punishment imposed in this case is for the charged conduct; using the past conduct as evidence is not the same as punishing him for it. Whether you agree with that distinction or not, FRE 404(b)(2) rests on it.
But you can work this idea into your FRE 403 objections--the danger of confusion or unfair prejudice lies in the jury attempting to punish the defendant for his past bad conduct, distracting from the conduct at issue.
And it can backfire. OJ Simpson is before most of your time (that is scary). But the prosecution offered a lot of evidence of Simpson's past abuse of Nicole (trying to show motive and identity). And some jurors, interviewed after the case, said they believed that focus was an effort to get them to convict Simpson for being an abusive person who hurt his wife in the past, without any proof he committed murder now.
