Heading off what one Washington lawyer called "a snarling cat fight" with Chief Justice Warren E. Burger, the policymaking body of the AMerican Bar Association yesterday easily defeated a resolution calling on him to repudiate or document his charge that up to half of the nation's trial lawyers are incompetent.

The House of Delegates acted after a half-hour debate in which Burger was attacked for "nativete unbecoming a Chief Justice" and was praised as a "good friend" of the ABA who has worked more closely with it than did any of his predecessors to improve the administration of justice.

The Illinois State Bar Association sponsored the resolution, which lost on a voice vote.

Urging adoption, William E. Rummage of Owensboro, Ky., denounced the "flippant" and "preposterous" support that Burger has provided for his claim that one-third to one-half of all courtroom advocates are inadequate in "serious" cases.

Finding "naivete" in Burger's statement that he had picked "a middle ground" between estimates made in "conversations . . . with literally hundreds of judges" over a long period, Rummage termed it "ironic" that such corroboration would be "unacceptable in "serious" cases.

Other than the principal sponsor of the resolution, Illinois Bar president Carole K. Bellows of Chicago, Rummage was the only delegate to speak for it. Speaking against it were four heavy-hitters in the ABA, including two of Bellows' predecessors, Barnabas F. Sears and Albert .E Jenner.

None of the resolution opponents made a serious case for the accuracy of Burger's estimate, though Sears said that after 50 years of practice he believes it "substantially accurate."

But none thought accuracy was the key issue, either. And all of the speakers agreed that the emphasis ought to be on major accomplishments, some of them credited to the ABA and Burger, in raising the level of trial advocacy with training and other programs.

Terming the resolution "monstrous," Sears said the ABA had no right to call Burger to account for remarks made elsewhere.

"I'm not defending the Chief Justice as a Chief Justice," he said. "I'm defending the Chief Justice as a citizen with the right to speak fully and freely." Jenner made a similar argument.

In contrast, Bellows said that the resolution "intends no disrespect" to Burger. She pointed out that in his speech Sunday to the ABA's mid-year meeting, Burger welcomed introduction of the resolution betwuse it calls attention to the problem of courtroom incompetence more forcefully than all of his speeches over more than a decade.

She cited an unverified report that in a survey of all federal judges conducted by a committee of the Judicial COnference of the United States, which Burger heads, only about 7 per cent of trial lawyers were rated unqualified.

The ABA's immediate past president, Justin A. Stanley, urged delegates to be "charitable" to their "good friend." Later in the day, they gave the Chief Justice an ovation when his presence in the hall was announced.

Washington delegate Lee Loevinger, a former assistant U.S. attorney general who warned against " a cat fight" with Burger, said it was "utter nonsense," to argue about the accuracy of the estimate - whether it is 50 per cent, as stated by Burger, or 20 per cent, as stated by ABA president William B. Spann Jr.

Loevinger drew laughter and applause when he ridiculed the notion that the answer to a charge of 50 per cent - or 20 per cent - incompetence is some lower percentage, such as 8 per cent. The question is, he said, "how are you going to qualify this?"

Turning to Bellows, Loevinger said, "Carole, maybe it's higher in St. Paul, where Warren Burger and I came from, than in Chicago."