As the Senate begins its debate today on G. Harrold Carswell's nomination to the Supreme Court, opponents of the controversial nominee are leaning heavily on the issue of his legal competence-or lack of it.

The issue was heightened last week when 457 prominent lawyers, including 25 faculty members at the Law School, signed a statement urging a rejection of the nomination, or "at the very least a reopening of the hearings to permit further inquiry."

Derek C. Bok, dean of the Law School, appeared last week with two other law deans and spoke against President Nixon's nominee at a news conference called to announce the release of the letter.

Incompetent

Bok, who circulated the statement among faculty at the Law School, Committee in which he said that Carswell showed "a level of compe-wrote a letter to the Senate Judiciary tence well below the high standards that one would presumably consider appropriate and necessary on the Court."

The statement said that "the nominee possesses a mental attitude which would deny to the black citizens of the United States-and to their lawyers, black or white-the privileges and immunities which the Constitution guarantees."

It also said that Carswell "does not have the legal or mental qualifications essential for service on the Supreme Court or on any high court in the land, including the one where he now sits."

Bok said last night that the faculty who signed the statement agreed "with the conclusions expressed in the letter with respect to his qualifications for the Supreme Court."

More Support

He also said that the number of signatures was deceptive because he had only 24 hours in which to circulate the statement. "I should think there would be more support since everyone I contacted in that short time agreed to sign," he said.

Critics of Carswell have pointed to his speech in 1948 in which he declared his support for white suprem-eey and his subsequent involvement in the organization of a private golf club discriminating against blacks.

But the law professors have also questioned his legal distinction, Louis H. Pollack, dean of the Yale Law School, testified before the Senate Judiciary Committee that Carswell appeared to possess "more slender credentials than any nominee in this century."

"One looks in vain for any opinion Carswell has written that has made a contribution to the law." Bok said last night.

"He has been reversed in cases appealed by a percentage that is more than in per cent and more than twiec as high as the average district jade," he said.

Only 22 Senators have announced their opposition to Carswell. and the most recent informal surveys indicate that the Southern judge's supporters have enough strength now to approve his nomination.