On July 10, 1975, Treasury Department agents in Cleveland received a tip that a machine gun had been shipped from there to Washington to be used in the planned jail escape of accused bank robber Terry Trice.

The agents checked further, and found that the gun was being sent by Greyhound Bus in a brown suitcase, and would be picked up in Wshington by a man named Jerry.

Washington-based agents of the Alcohol, Tobacco and Firearms Bureau of the Treasury Department went to the Greyhound station here where they found such a bag. They could plainly feel the outline of a gun through the soft side of the suitcase.

The agents then forced the suitcase open, saw the gun inside, closed it and waited for someone to claim it. The next day, it was claimed by Jerome Jones, and he was arrested.

Yesterday, the U.S. Court of Appeals reversed the convictions of Jones and Judy E. Martin, who was convicted of shipping the gun here, because the agents failed to get a search warrant before opening the suitcase.

Chief Judge David L. Bazelon said that the agents who examined the bag in the Greyhound station should have obtained a warrant after they located the suitcase and before they actually forced it open. Failure to do so violated the suspects. Fourth Amendment right against illegal search and seizure, Bazelon found.

Bazelon and Circuit Judges Edward A. Tamm and Rogers Robb rejected the government's contention that agents had to forego warrant because they were operating under "exigent circumstances."

On the contrary, said Bazelon, there was "obviously little likelihood that the suitcase could have been moved without the agents' being aware of it," so they could have gone ahead and gotten a warrant before opening it.

Although he said it was not necessary to reach the issue, Bazelon added he was unsure whether it was proper that the agents even felt the side of the suitcase to locate the bulging gun. Resolving the legality of an exterior examination of the suitcase "would be close and difficult," he said.