Frederick Crowley quit his job as a Navy lawyer Sept. 29. Less than two weeks later he took out a two-column, three-inch ad in The Wall Street Journal to announce his availability to take cases against the government.

For the past four years, Crowley said in the ad, he had represented the Navy in its billion-dollar dispute with Litton Systems over shipbuilding contracts. That dispute involved "the largest claims ever filed against the U.S. under a government contract," the ad said.

Crowley's punchline was simple and to the point:

"He seeks association with law firms and representation of contractors and others with claims against any agencies of the U.S. government."

Sen. William Proxmire (D-Wis.) called Crowley's ad "the most blatant example of the revolving door used by the legal profession that I have ever seen . . .

"I leave it to legal profession to determine whether such conduct is ethical." Proxmire continued. "Common sense tells me this is wrong, and it may help to explain why the Navy got such bad legal advise during the shipbuilding claims dispute and why contractors are filing so many claims against the government."

According to legal authorities, Crowley's ad neither violates U.S. conflict laws nor bar association canons of ethics as long as he does not take any case in private practice that he dealt with while he worked for the Navy.

"I put a lot of thought into the ad," said Crowley, who practiced law in Washington for 27 years specializing in contractor claims against the government before joining the Navy general counsel's office.

"I don't see that I'm violating any rules," he added.

He said Litton was "the only opponent I ever had in the Navy."

Fred Grabowsky the bar counsel in charge of discipline for the D.C. Bar, said Crowley can even represent Litton as long as it has nothing to do with the shipbuilding cases he dealt with while a Navy lawyer.

Saul Katz. assistant Navy general counsel, said he believes a bar cannon against "the appearance of impropriety" would keep Crowley from working for Litton.

The D.C. Bar's ethics committee currently is trying to tighten its rules to block the "revolving door," but its efforts have met with great opposition from government lawyers and attorneys in private practice.

On the other side, Adm. H. G. Rickover, director of the Naval Nuclear Propulsion Program, has attacked for years the movement of lawyers in and out of government in the contract claims field.

He said in congressional testimony two years ago that Washington law firms that specialize in claims against the government "hire away some of the few experienced lawyers we have."

In earlier congressional testimony, he had said. "I personally have no respect for ex-government officials who, after once learning the inner workings of government, then leave its employ to exploit this knowledge for personal profit at the expense of the government."

He also has tried unsucessfully to get Armed Services Board of Contract Appeals to disqualify law firms from a case if one of their employes fomerly worked for the government on that case.

"Government attorney, however," Rickover told a congressional committee, "are usually reluctant to find any conflict of interest in these kinds of situations. Perhaps they do not want to preclude the prospect of a lucrative job offer for themselves at a later date."

Proxmire attacked the Litton settlement that Crowley claimed in his ad that he had a major role in developing Proxmire called the settlement "a bailout" for the shipbuilders.

He said Crowley's ad "suggests that claims against the government have become a bonanza for the claims attorneys as well as for the contractors."

Crowley said the only responses he has gotten from the ad, which ran Wednesday, have been calls from other newspapers wanting to sell him advertising space. But he isn't daunted. For a lawyer working alone, he said one or two clients in major claims cases are enough.

"I'm not looking for run of the mill legal business," he said.