## Facts

- Defendants were charged with a marijuana-smuggling scheme involving flights from Mexico into California.
- Two flights successfully transported marijuana to Palmdale, California.
- During one flight, the aircraft landed at Borrego Valley Airport (Borrego Springs, in the Southern District of California) to refuel and to place a call coordinating the Mexico pickup point.
- Defendants were indicted in the Southern District of California for conspiracy to import marijuana, importation/attempted importation, and possession with intent to distribute.
- A key government witness, Dillon (a codefendant who pleaded guilty), testified for the prosecution; he had previously committed perjury before the grand jury and had an Army-related psychiatric history.
- Shortly before trial, defendants sought to present a psychiatrist and a psychologist to opine—based on courtroom observation and Dillon’s Army evaluation—on Dillon’s competency and reliability, essentially that he would lie when it served his interests.
- The district court excluded the proposed expert testimony; the jury convicted defendants on multiple counts.

## Issues

1. Whether venue in the Southern District of California was proper for the conspiracy and substantive drug counts given that much conduct occurred elsewhere.
2. Whether the district court erred by excluding psychiatric and psychological expert testimony offered to attack a key witness’s competency and credibility (truthfulness).
3. Whether the trial court abused its discretion in handling witness competency and leaving credibility determinations to the jury despite the witness’s perjury and psychiatric history.

## Decision

- The Ninth Circuit affirmed the convictions.
- Venue was proper in the Southern District of California for the conspiracy because the Borrego Springs refueling stop and related coordination call were overt acts in furtherance of the conspiracy occurring in that district.
- Venue was proper for the substantive drug counts because importation and possession with intent to distribute were treated as continuing offenses, permitting prosecution in any district where the offenses began, continued, or were completed.
- The district court acted within its discretion in excluding expert testimony offered solely to opine on the witness’s reliability and credibility.
- The trial judge properly determined competency without expert assistance and allowed impeachment through conventional methods (cross-examination about perjury, plea benefits, and motives).

## Legal Principles

- Conspiracy is a continuing offense triable in any district where an overt act in furtherance of the conspiracy occurs.
- Under 18 U.S.C. § 3237(a), offenses that begin in one district and continue into another may be prosecuted in any district where the offense was begun, continued, or completed; drug importation and possession with intent to distribute may qualify as continuing offenses for venue purposes.
- Competency of a witness is primarily for the trial court to decide and is reviewed for abuse of discretion.
- Credibility determinations are for the jury; expert testimony offered principally to tell the jury whether a witness is truthful is generally inadmissible because it invades the jury’s role and risks undue prejudice.

## Conclusion

The Ninth Circuit upheld venue based on overt acts and the continuing-offense doctrine, and it approved the exclusion of psychiatric and psychological opinions aimed at portraying a government witness as inherently untrustworthy, leaving credibility assessment to the jury and competency to the trial judge’s discretion.


United States v. Barnard, 490 F.2d 907 (9th Cir. 1973)