Roy L. Williams, seeking to eliminate any possible obstacle to his expected election here this week as general president of the International Brotherhood of Teamsters, went before a major Teamsters unit today to defend himself against federal charges that he conspired to bribe a member of Congress.

Williams' appearance before a meeting of Teamsters Joint Council 42 of the Los Angeles area, the largest council in the nation's largest union, marks his first extended public defense against allegations that he plotted to let Sen. Howard W. Cannon (D-Nev.) buy Teamsters' land here in return for Cannon's efforts to block a trucking deregulation bill.

The charges were made in an indictment issued May 22 by a federal grand jury in Chicago.

Williams contended today that the allegations were the product of "antiunion bias," designed to embarrass him and the Teamsters union.

"I am sure that I will be vindicated when the case gets to court," he said. "Sen. Cannon has said that he met me one time and that there were others in the room" where and when the meeting took place, Williams said.

"We certainly did talk about nothing except deregulation of the trucking industry and the [operation of] the Interstate Commerce Commission," Williams said of the meeting in Cannon's Las Vegas office on Jan. 10, 1979. However, the Teamsters leader said his session with Cannon involved no improper solicitation of the senator's support for the union's drive to stop the deregulation bill that became law last July.

Williams also defended his recent appearance before the Senate permanent investigations subcommittee, where he invoked the Fifth Amendment several times in lieu of answering questions about his union's financial dealings.

He said he had tried to find out beforehand from the committee's investigators "what loans they were talking about" so that he might be better able to answer the committee's questions. But his efforts failed, leaving him "no other alternative but to take the Fifth Amendment, which I did," Williams said.

"Because I exercised my constitutional right, I became the target" of "anti-union" members of the subcommittee, Williams said.

Williams' appeal won the support he sought from the rank-and-file delegates of the California joint council.

Williams' only opponent is Peter Camarata of the dissident Teamsters for a Democratic Union, which has about 40 delegates among the convention's 2,200 delegates.