A federal judge in San Francisco has granted a conservative legal group's bid to enter the case against Jerry Alfred Whitworth and argue that the accused Soviet spy should be subject to the death penalty if convicted.

U.S. District Judge J.P. Vukasin Jr., in an order filed last week, said he would permit the Washington Legal Foundation to join the case as a "friend of the court" to argue that Whitworth, 45, could face the death penalty. Vukasin set Sept. 12 for a hearing on the issue.

Federal judges hearing the cases against John Anthony Walker Jr. and his brother, Arthur James Walker, had rebuffed the legal group's attempts to argue for the imposition of capital punishment in those cases.

Federal prosecutors have said they believe there has been no valid federal death penalty for espionage since 1972, when the Supreme Court invalidated a wide array of capital punishment statutes.

The Ninth Circuit U.S. Court of Appeals in San Francisco overturned last year a ruling by U.S. District Judge Samuel Conti holding that the death penalty could be imposed in the case of convicted spy James Durward Harper.

"We will probably just simply call the court's attention to the Ninth Circuit's decision in U.S. v. Harper which settles the issue," said Assistant U.S. Attorney William Farmer, who is leading the prosecution of Whitworth.

Whitworth, a retired Navy senior chief radioman, is accused of giving classified documents and secret coding cards to John Walker, his Navy buddy.

Don Kraft of the Washington Legal Foundation said the group, which is also representing eight conservative congressmen, was "certainly encouraged" by Vukasin's order. "We feel that the death penalty is a proper punishment for this injurious crime," he said.