## Facts

- Two armed men entered Frank L. Goodell’s King County residence; one guarded occupants while the other forced Goodell to open a store safe and surrender money.
- Roy Earl Oswalt was identified as one of the perpetrators and was charged with robbery and first-degree burglary arising from the same incident.
- Oswalt presented an alibi through August Ardiss, a Portland restaurant operator, who testified Oswalt was in his restaurant on July 14, 1961 at times making it practically impossible for him to be in Seattle during the crime.
- On cross-examination, Ardiss stated that, to the best of his knowledge, Oswalt had been in the restaurant “every day” for the prior “couple of months.”
- In rebuttal, over objection, the State called a Seattle police detective who testified he spoke with Oswalt in Seattle on June 12, 1961 and Oswalt said he had arrived in Seattle a couple days earlier, coming from Portland.
- The jury convicted Oswalt on both charges, and he appealed the admission of the rebuttal testimony.

## Issues

1. Whether the State may introduce extrinsic rebuttal testimony to contradict an alibi witness’s cross-examination statement about the defendant’s whereabouts on a date about one month before the charged crime.
2. Whether such contradiction constitutes impermissible impeachment on a collateral matter.
3. If error occurred, whether admitting the rebuttal testimony was harmless or prejudicial.

## Decision

- The Washington Supreme Court reversed and remanded for a new trial.
- The detective’s rebuttal testimony concerned a collateral matter and was inadmissible impeachment by contradiction.
- The erroneous admission was prejudicial because it substantially undermined the credibility of a key alibi witness.

## Legal Principles

- A witness may not be impeached by extrinsic evidence on matters collateral to the principal issues being tried.
- A matter is collateral if the fact could not have been introduced for any purpose independent of contradicting the witness.
- When an improper collateral impeachment targets a central defense witness (such as an alibi witness), the error is prejudicial if it may have affected the verdict.

## Conclusion

The court held that the State improperly used extrinsic rebuttal evidence to contradict an alibi witness on a collateral point elicited on cross-examination, and because the impeachment could have materially weakened a key defense, the convictions were reversed for a new trial.


State v. Oswalt, 62 Wn.2d 118, 381 P.2d 617 (Wash. 1963)