## Facts

- A U.S. Park Police sergeant conducted surveillance of a Washington, D.C. area known for drug activity from an elevated location using binoculars.
- The sergeant observed James A. Foster in a parked car and testified he saw conduct consistent with drug sales, including receiving money and handing over small white objects.
- The sergeant further testified he saw Foster handle two clear plastic bags, place them in a brown paper bag, and move and discard the bag near fences by an apartment building.
- Officers responding to the sergeant’s radio description arrested Foster and found $311 on him.
- Another officer recovered the brown paper bag, which contained 51 packets of crack cocaine.
- The sergeant’s identification was the only direct evidence linking Foster to the cocaine and was the prosecution’s central proof at trial.
- A jury convicted Foster of possessing more than five grams of crack cocaine with intent to distribute and committing the offense within 1,000 feet of a school.

## Issues

1. Whether Federal Rule of Evidence 501 permits a law enforcement eyewitness to refuse at trial to disclose the exact location of the surveillance post from which the witness made observations.
2. Whether the district court erred by sustaining relevance objections that restricted cross-examination aimed at testing the officer’s ability to perceive and describe other individuals involved in the observed events and whether the officer radioed descriptions of them.

## Decision

- The D.C. Circuit affirmed the convictions.
- The court held the government did not establish, on this record, any privilege under Rule 501 that justified withholding the officer’s exact surveillance location from cross-examination.
- The court held the trial court erred in treating certain defense questions about the officer’s perceptions and descriptions of other individuals as irrelevant.
- The court concluded the trial errors were harmless in light of the overall record and the cross-examination that was permitted.

## Legal Principles

- Federal Rule of Evidence 501 allows recognition of privileges only when justified by “reason and experience”; it does not itself create a categorical privilege shielding an officer’s observation-post location at trial.
- When an eyewitness is central to the prosecution’s case, the defendant’s Sixth Amendment right to cross-examine that witness carries special weight, particularly as to matters bearing on perception and identification.
- Relevance under Rule 401 is a threshold inquiry; evidence is relevant if it has any tendency to make a consequential fact more or less probable, and it is not properly excluded by labeling it “marginally” relevant.
- Restrictions on cross-examination and related evidentiary errors may be affirmed if the government shows they were harmless and did not affect the verdict.

## Conclusion

The D.C. Circuit declined to recognize a broad law-enforcement privilege permitting an eyewitness officer to conceal a surveillance location without a specific showing, and it ruled that limiting cross-examination of a critical identification witness on relevance grounds was erroneous, but the errors did not warrant reversal because they were harmless.


United States v. Foster, 986 F.2d 541 (D.C. Cir. 1993)