The conviction of Roy L. Williams, the president of the International Brotherhood of Teamsters, on conspiracy to bribe and fraud charges, will add to a growing burden of problems for the country's largest union, once impervious to challenges internally and in its main industry.
The verdict is unlikely to have an immediate impact on the IBT because Mr. Williams and four codefendents are appealing their case - a legal processes that could let Williams remain free and in control of the union through most of 1983 or even longer.
But the long-term effects could be important:
* Williams's conviction on 11 counts of bribery, conspiracy, and fraud could prod the 98th Congress to act early next year on a labor-racketeering bill that could provide machinery to attack deeply rooted corruption wherever it might exist in organized labor.
* It could set off a leadership struggle within the Teamsters, not spurred by dissidents who have been demanding a cleanup in IBT, but involving established and ambitious union officials considered likely to keep the Teamsters pretty much on its present course.
* It undoubtedly will add to the union's growing problems in an industry that is in ferment as a result of the deregulation of trucking.
* And it could have far-reaching legal implications, not only for labor prosecutions, but also in other criminal proceedings. US District Court Judge Prentice Marshall, in Chicago, admitted very extensive wire-tapping evidence in the trial. He has described the case as ''the most significant electronic eavesdropping case to be presented.'' Tapes played for jurors during the trial, and reviewed in the 27 hours of deliberations, will be a key issue in appeals that are considered almost certain to go to the US Supreme Court.
Williams, who will be sentenced in February, could face five years on each of the 11 counts. The convictions were on charges that Williams and his associates tried to bribe Sen. Howard Cannon (D) of Nevada to fight trucking deregulation in Congress by offering to sell country club property owned by a Teamsters fund to him for $1.4 million - less than the $1.6 million price it brought when sold on the open market. According to the government, the deal was thwarted by a management concern appointed by the Labor Department two years earlier to supervise the pension fund's assets.
Williams' conviction made him the third of the last four Teamsters presidents to be found guilty in criminal trials.
Under the Landrum-Griffin Act of 1959, Williams will have to give up his $225 ,000 IBT presidency, which ordinarily would run until 1986, if his conviction stands up. Under present laws, he cannot be forced out of office otherwise.
A labor-racketeering bill with retroactive provisions passed the Senate in July but is now bottled up in the House Labor Standards subcommittee. Senate sponsors plan to revive it in the 98th Congress, in much the same form. If it passes in 1983, Williams could be forced from office.
What worries many in the union now is the impact of the conviction on the trucking industry.
The powerful IBT has come into difficult times in recent years. It has lost half a million members from the more than 2 million on its roles in the late 1970s.
Its industry is in trouble. Government deregulation of trucking, which went into effect in July 1980, has permitted nonunion companies to undercut those under costly IBT contracts. Many unionized operators have shut down, while more than 10,000 new companies have registered with the Interstate Commerce Commission to carry freight at 20 to 30 percent less than union competitors.
To help employers with union contracts, the Teamsters agreed last May to a virtual freeze of wages for 39 months and gave other concessions without winning guaranteed protection of jobs. This has led to increased dissension within the union - although not enough, so far, to be more than a harassment for the present leadership and increased difficulties in maintaining union-contract trucking and union jobs.