## Facts

- Crystal York, Serrano’s girlfriend, attempted to smuggle methamphetamine by air from San Francisco to Hawaii for Serrano and Martinez.
- York was arrested at the airport and agreed to cooperate with law enforcement.
- At officers’ direction, York called Serrano and asked him to pick her up at the airport.
- Serrano did not have a car and asked Martinez to drive him to the airport.
- When Serrano and Martinez arrived at the airport, law enforcement arrested them.
- Martinez was charged with importing methamphetamine.
- At trial, Martinez claimed he thought he was only giving Serrano a ride to pick up his girlfriend and did not know anything about drugs.
- Over Martinez’s objection, the district court admitted evidence that Martinez had previously been convicted of importing heroin (conduct in 1986; conviction entered in 1993).
- The court instructed the jury that the prior conviction could not be used to show Martinez’s bad character or a propensity to commit the charged offense, but could be considered on whether he knew why he was driving Serrano to the airport.
- The jury convicted Martinez, and he appealed, challenging the admission of the prior heroin-importation conviction.

## Issues

1. Whether the district court erred under Federal Rule of Evidence 404(b) by admitting Martinez’s prior heroin-importation conviction to prove knowledge and intent in the charged methamphetamine-importation case.
2. Whether the prior-conviction evidence, even if admissible under Rule 404(b), should have been excluded under Federal Rule of Evidence 403 because its probative value was substantially outweighed by the danger of unfair prejudice, given the time gap and the different drug involved.

## Decision

- The Ninth Circuit affirmed Martinez’s conviction.
- The court held the district court did not abuse its discretion in admitting the prior heroin-importation conviction for the limited purposes of proving knowledge and intent.
- The court held the district court did not abuse its discretion under Rule 403 in concluding the evidence’s probative value was not substantially outweighed by unfair prejudice, particularly in light of the limiting instruction.

## Legal Principles

- Evidence of prior crimes or acts may be admitted under Rule 404(b) for non-character purposes such as proving knowledge or intent, when those matters are genuinely disputed.
- In drug importation prosecutions, a prior importation conviction may be probative of whether a defendant knew the purpose of the trip and intended to participate, especially when the defendant offers an innocent explanation for his conduct.
- Differences between the prior and charged conduct (including the type of controlled substance) do not automatically bar admission; similarity in the nature of the conduct may be sufficient for relevance.
- Remoteness in time is a factor in the Rule 404(b) analysis and in Rule 403 balancing, but it does not automatically make the evidence inadmissible.
- Under Rule 403, trial courts have broad discretion to weigh probative value against unfair prejudice, and a clear limiting instruction reduces the risk that the jury will use the evidence for an improper propensity inference.

## Conclusion

United States v. Martinez, 182 F.3d 1107 (9th Cir. 1999), upheld the admission of a defendant’s prior heroin-importation conviction in a later methamphetamine-importation trial where the defendant claimed he was innocently providing a ride, concluding the evidence was properly admitted to show knowledge and intent under Rule 404(b) and was not unfairly prejudicial under Rule 403 given the limiting instruction.


United States v. Martinez, 182 F.3d 1107 (1999)