ASHINGTON, March 30 — The Supreme Court ruled unanimously on Tuesday that release of the death-scene photographs of Vincent W. Foster, the Clinton administration's deputy White House counsel who killed himself in 1993, would be an unwarranted invasion of the privacy of Mr. Foster's surviving family members.

The court said the photographs should be shielded from disclosure in a suit brought under the Freedom of Information Act by a California lawyer, Alan J. Favish, who said he doubted the conclusion reached in five separate investigations that Mr. Foster committed suicide.

Mr. Favish's "bare suspicion" was an insufficient basis for overcoming the family's privacy rights in light of the scope of the official investigations, the court said, adding that courts should not have to "engage in a state of suspended disbelief with regard to even the most incredible allegations."

Justice Anthony M. Kennedy's opinion overturned a 2002 ruling by the United States Court of Appeals for the Ninth Circuit, in San Francisco, which found Mr. Favish was entitled to obtain 4 of the 11 photographs he had sought. All 4 were partial views of Mr. Foster's body as it lay in Fort Marcy Park in McLean, Va. One photograph showed a gun in Mr. Foster's right hand.

Mr. Favish filed his lawsuit after Kenneth W. Starr, the independent counsel whose office had the pictures at the time — they are now held by the National Archives — refused to release the photographs. Mr. Foster's sister, Sheila Foster Anthony, and widow, Lisa Foster Moody, intervened in the case to oppose the suit.

Mr. Starr and the two family members invoked one of the Freedom of Information Act's exemptions, Exemption 7(c), which provides that records or information compiled for law enforcement purposes should not be disclosed if their production "could reasonably be expected to constitute an unwarranted invasion of personal privacy."

The case therefore presented two legal questions. The first was whether the interest in "personal privacy" protected by the exemption could be invoked not only by the individual whose records were sought, but also by family members. If the answer was yes, the second question was whether release of these photographs would be an unwarranted invasion of the family's privacy. The answer required a balancing of the privacy interest against the public interest in disclosure.

As to the family's privacy concerns, Justice Kennedy said respect for bodies of the dead had a long tradition in culture and law, which Congress presumably understood when it drafted the information act. He said the court was aware of "the right of family members to direct and control disposition of the body of the deceased and to limit attempts to exploit pictures of the deceased family member's remains for public purposes."

Justice Kennedy said that while the family's interest could theoretically be overcome by a strong public interest in disclosure, Mr. Favish had failed to demonstrate such an interest in this case, National Archives v. Favish, No. 02-954. He said the court would not "in this single decision" try to define the public interest that might be sufficient under other circumstances.

In this case, he said, where the person requesting the information is trying to show that public officials acted negligently or improperly, "the requester must produce evidence that would warrant a belief by a reasonable person that the alleged government impropriety might have occurred."

Lucy Dalglish, executive director of the Reporters Committee for Freedom of the Press, which filed a brief for Mr. Favish, said the ruling would impede public disclosure of information about suspicious deaths. "I don't know how you can expect requesters to prove a negative before they are entitled to a record under the Freedom of Information Act," Ms. Dalglish said.

Separately on Tuesday, the court ruled unanimously that customs officials do not need a warrant or any particular degree of suspicion in order to remove and search the gas tank of a vehicle that is crossing the border. Chief Justice William H. Rehnquist wrote the opinion, United States v. Flores-Montano, No. 02-1794, which overturned a ruling by the Ninth Circuit.

The case grew out of a search of a station wagon's gas tank at the Otay Mesa, Calif., border crossing. Inside was 80 pounds of marijuana. "The government's interest in preventing the entry of unwanted persons and effects is at its zenith at the international border," Chief Justice Rehnquist said.

Robert C. Bonner, commissioner of the Customs and Border Protection Service, said the decision also applied to searches of cargo containers at ports and would prove "vital to our mission" of intercepting terrorism at the border.