Prominent Washington attorney Thomas G. (Tommy the Cork) Corcoran faces an ethics investigation because of the recent disclosure of his apparently unprecedented lobbying of two Supreme Court justices in 1969 in connection with a pending case.

The investigation will be conducted by the board on professional responsibility of the District of Columbia Bar. The result could be exoneration, disbarment or any of several in-between actions.

Bar sources said that Justice Willian J. Brennan Jr. may be asked to give his version of the episode. Whether he would do so would be "solely a matter for his own judgement," according to Eugene Gressman, an expert on the court. The second justice, Hugo L. Black, is dead.

The investigation was triggered by a letterto the bar from ADM. H. G. Rickover, who is not a lawyer. Rickover, 79, is known as the father of the nuclear Navy. Corcoran, 78, was one of President Roosevelt's "brain trusters." They are long-time adversaries.

Rickover learned of Corcoran's reported lobbying from a Dec. 3 Washington Post excerpt of "The Brethren," a book by Bob Woodward and Scott Armstrong about the inner workings of the Supreme Court. A reporter, over a three-day period, was unable to reach Corcoran for comment.

In his letter, Rickover recommended that the bar "investigate whether Mr. Corcoran actually contacted the Supreme Court justices as reported; determine whether the behavior of Mr. Corcoran violates the legal profession's code of professional resonsibility, and, if so, take appropriate legal action."

He sent copies of the letter to five federal officials and Leonard Janofsky, president of the American Bar Association. The ABA "bears responsibility to see that the code is not simply window dressing," Rickover told Janofsky.

District Bar president John H. Pickering forwarded the complaint to the board with a coy of a letter in which he told Rickover that private contacts with judges relating to pending cases are "generally condemned" by the ABA code.

"They are also usually counterproductive, as appears to have been the case in the instance described in the cited article," Pickering wrote. "Nevertheless, they must be regarded seriously since they give the appearance of undue advantage and can impair public confidence in the legal professionand in the impartial administration of justice."

ABA president Janofsky told a reporter that the book's account of Corcoran's actions, "if true," struck him personally as "a very, very serious violation of the canons of ethics."

The account says that Corcoran first went to see Black, an old friend, while the court had before it a petition by the El Paso Natural Gas Co., the world's largest gas pipeline venture, for a rehearing of an antitrust ruling requiring El Paso to divest its holdings in the West.

Corcoran's law firm had been retained by Colorado Interstate Gas Corp., which also had fought the ruling, but his name had not appeared on the petition or on other briefs and papers.

The unsuspecting justice was "shocked" when Corcoran complained that the ruling was " a great injustice," Woodward and Armstrong wrote. "Black cut his old friend off quickly. No. He shooes Corcoran out of his office." In 32 years on the court Black had never had the arm put on him in such an overt way in hs own chambers," the authors wrote.

Corcoran next tried Brennan, who also was caught unawares. "Brennan stood," the book says. "He said that he, of course, could not and would not ever discuss a pending case, and showed corcoran to the door. He immediately went to tell his clerks. Something awful just happened, he said." i

Brennan -- but not Black -- reported the visit to fellow justices at one of the court's regular secret conferences. In the end, however, the court took no action against Corcoran for what the book terms his "improprieties."

The court almost never grants rehearing petitions, and it didn't grant El Paso's.

The authors give no hint that the justices considered invoking the Supreme Court's Rule 5 (1), which says that the "private and professional characters" of members of the court's bar "shall appear to be good." They say that Chief Justice Warren E. Burger viewed the visit by Corcoran - a member of the court's bar since 1936 -- as "stupid, but trivial." c

Six months ago, however, burger, invoking that rule, alone dissented when the court admitted to its bar two lawyers who had been censured by state bars.

The code of professional responsibility says that "the integrity of the profession can be maintained only if conduct of lawyers in violation of the disciplinary rules is brought to the attention of the proper officials. A lawyer should reveal voluntarily to those officials all unprivileged knowledge of conduct of lawyers which he believes clearly to be in violation of the disciplinary rules."

Disciplinary rule 7-110 says: "In an adversary proceeding, a lawyer shall not comunicate . . . as to the merits of the cause with a judge . . .before whom the proceeding is pending. . . ."

The authors do not suggest that any of the justices who are members of state bar associations and the ABA raised the possibility of referring the Corcoran matter in the U.S. District Ourt committee that, in 1969, had the investigatory and disciplinary powers now held by the District of Columbia Bar's board on professional responsibility.

Board investigations, which are confidential, can lead to dismissal of allegations or to an informal admonishment. They also can lead to charges to be heard by a hearing committee, which can recommend dismissal from the bar. If it recommends a specific disciplianry action,the case becomes public.

The board can dismiss, issue a public reprimand or recommend to the D.C. Court of Appeals a more severe disciplining, such as suspension or disbarment.

The clash between Rickover and Corcoan involves huge claims filed against the Navy by shipbuilders, particularly those owned by conglomerates. Rickover relentlessly battles claimes he views as unjustified and excessive or even improper Corcoran is a relentless advocate of one of Rickover's target defense contractors, Newport News Shipbuilding & Dry Dock Co., a division of Tenneco Inc.

"Corcoran lobbied extensively to prevent my reappointment" as deputy commander for nuclear power of the Naval Sea Systems Command, Rickover testified on Capitol Hill in March 1977.

He returned to the subject two years later in Senate testimony in which he referred to "this lobbyist," without naming Corcoran.

In his presence, Rickover said, Corcoran telephoned the secretary of the Navy to urge that the admiral, if reappointed, be "assigned to duty somewhere -- perhaps to Kamchatka, which is 12,500 miles from Washington -- where [Rickover] would not be involved in his client's activities with the Navy.