FRE 404(b) – one of the most controversial rules of evidence. Known as the rule of exclusion, it attempts to prevent the prior bad acts of a witness from being admitted into evidence because those acts are often used as evidence of propensity – an inclination to behave in a particular way. However, under the exceptions outlined in FRE 404(b)(2), prior bad acts are often admitted therefore, making 404(b)(2) a rule of inclusion, not exclusion.

FRE 404(b)(1) explicitly reads “evidence of any other crime, wrong, or act is not admissible to prove a person’s character in order to show that on a particular occasion the person acted in accordance with the character.”[1] This means that a prior bad act, or crime, cannot and should not be used for propensity purposes. For example, an attorney cannot argue that because a person committed a bad act in the past, they committed the current crime charged. This prevents the party who committed the prior bad act from being unfairly prejudiced by the prior bad act in front of the jury. In theory, it stops the jury from considering a person’s past actions and forces them to focus on the present.

But it is not that simple. This “bad-act” evidence IS permissible and CAN AND WILL be admitted under the exceptions outlined in Rule 404(b)(2), which includes:

  1. motive,
  2. opportunity,
  3. intent,
  4. preparation,
  5. plan,
  6. knowledge,
  7. identity,
  8. absence of mistake, or
  9. lack of accident.[2]

Under any of these exceptions, a person’s prior crime or bad act may be admitted and referenced during a trial. Courts are permitted to admit the prior acts, regardless of the propensity inference or prejudicial effect because of the evidence’s probative value that arises from the exceptions. For example, when evidence a defendant’s prior act has the same motive as the one in question, it is admissible. If the prosecution can prove that the intent, the plan, the preparation, or the opportunity is the same for both the current and past acts, then the evidence is admissible. Courts hold that if you prove any one of these nine exceptions listed in the statute, prior bad act evidence is admissible.[3] Courts then give a limiting instruction to explain the reason for admitting evidence of the prior bad act. However, admitting this evidence, regardless of a limiting instruction, eliminates the rule of exclusion and transforms it into the rule of inclusion.

The issue is that the prior bad act is not what the jury should be focusing on – it leads to mini trials within trials. The jury should be focused on the matter in question. Hence the problem: is the jury really deciding the case on a person’s prior bad act or the accused offense? Is the jury really following the judge’s instructions and considering the evidence only for a limited purpose? Or would they do both by bypassing the judge’s limiting instruction and using the prior bad act AND using evidence of the accused offense to convict?

Scholars differ on the inclusion or exclusion of “bad-act” evidence. The question has become: is 404(b) a rule of exclusion, while 404(b)(2) is a rule of inclusion? On one end of the spectrum, scholars such as Susan Marlene Davies argue that “past behavior may be highly probative of a defendant’s behavior in similar circumstances.”[4] In sum, Davies believes that jurors should look at the whole person, including their past, because she finds it may help them accurately gauge how the person acted in the current instance – inclusion. But people can change, can’t they? Why should a juror view a defendant on a past crime when that is not the current accused offense? Juries should not be allowed to convict a defendant for robbery in 2021, simply because the defendant had previously committed another robbery in 2013. The floodgates of litigation would open wide leading to a plethora of baseless convictions supported by little evidence related to the present crime charged.

Not all scholars side with Davies. Professor Roger Park challenges her by arguing that evidence of an alleged crime where the defendant has been proven guilty, coupled with proof of the defendant’s engagement in similar-type conduct, could be highly incriminating and prejudicial – exclusion.[5] There MUST be enough evidence of the alleged crime to prove, either beyond a reasonable doubt (criminal) or by a preponderance of the evidence (civil), the defendant’s guilt or liability. Park raises a thought-provoking argument – if there is evidence to prove the alleged crime AND evidence of the defendant’s prior-acts, the prejudicial effect is outweighed by any probative value. More specifically,

the appropriate question for gauging the probative value of other-acts evidence is … whether – when viewed in the context of other evidence already pointing toward a defendant’s guilt – a defendant who has committed the other act is more likely to be guilty than if he had not committed the other act.[6]

Would a jury be more likely to convict a defendant of an accused crime knowing the defendant has committed a similar act in the past? Yes. The scale must tip in favor of exclusion – a jury cannot decide a case based on prior-act evidence that is not relevant to the alleged crime. The exceptions create the opportunity of inclusion, but that evidence cannot be introduced.

Let’s walk through a few hypotheticals:

Five years ago, A assaulted B in a bar with a broken beer bottle (A’s bad act #1). Present day, A and B again have a physical altercation where A is accused of assaulting B. This time A claims self-defense. Would the prosecution be successful in bringing in the prior assault against A? Possibly – the prosecution COULD argue the exceptions: motive, opportunity, plan, or preparation.

What about if X, seeking revenge against Y, kidnaps her pet. X is caught and convicted (X’s bad act #1). Years later, X is accused of kidnapping Z’s pet because X and Z dislike each other. X argues he did not commit the latter act but found the lost pet. The prosecution intends to admit the prior crime against X under 404(b)(2) common scheme or plan. Does anyone not think there will be a conviction after hearing the prior bad act?

Both hypotheticals COULD lead to the introduction of prior bad acts. 404(b) would prevent these acts from ever entering a jury’s mind, but it is evident that the 404(b)(2) exceptions create the issue of inclusion. Even with a limiting instruction, the bad acts will always remain in the back of the jury’s minds during jury deliberations. A jury may tend to overlook the necessary evidence and convict solely based on the prior-act evidence.

The jury’s perception of the defendant may become skewed due to the introduction of the prior bad act. It is human nature to hear or see something and want to judge someone by it. Courts often hold that people should be looked at for what they have done, not who they are[7] – but there will always be judgment. There will always be that one juror, or twelve, who look at a person and their past to define what they did. Jurors tend to overvalue this evidence.[8] Courts have succeeded in excluding prejudicial evidence including 404(b) bad acts, but as previously discussed, the list of 404(b)(2) exceptions may lead to improper inclusion.

A point to ponder: if a person’s “bad-act” evidence cannot be used as propensity evidence, but can be used to show motive, intent, plan, etc. in the Rule 404(b) exceptions, is it similar to a hearsay statement that is not being used “for the truth of the matter asserted?” Is it likely the jury hears an out-of-court statement and does not take it for its truth? Doubtful. The party can offer a statement not for its truth, but the statement is floating around the courtroom for the jury to use either for or against a party to the litigation. A jury will take the statement for its truth – it is out there. And a jury will also consider a prior bad act as evidence the party has acted in the same manner again.


[1] Fed. R. Evid. 404.

[2] Id.

[3] United States v. Dupree, 870 F.3d 62, 76 (2d Cir. 2017). See also United States v. Kadouh, 768 F.2d 20, 21 (1st Cir. 1985).

[4] Steven Goode, It’s Time to Put Character Back into the Character-Evidence Rule, 104 Marq. L. Rev. 706, 762 (2021).

[5] Id.

[6] Id. at 763.

[7] Id. at 712.

[8] Id. at 721.