The tenor of a long dispute over whether Litton Industries is a labor-practice outlaw of record proportions has changed for the better. For the past year and a half, a campaign by labor unions and religious groups has been denouncing Litton as the ''J.P. Stevens of the 1980s.'' Campaign organizers say the number of Litton's labor-law violations outdoes any other company in the nation, past or present.
Litton, a far-flung, high-technology conglomerate based in Beverly Hills, has maintained its innocence and claimed healthy labor relations throughout.
But the National Labor Relations Board has shown skepticism toward the Litton record, and events during the last couple of months of have mounted pressure against the company.
Then, at a shareholders meeting last weekend, Litton chairman Fred W. O'Green pleasantly surprised the union campaign. Mr. O'Green proposed a study group of two labor representatives, two Litton representatives, and a neutral chairman to review the company's labor relations and how to improve them.
While both sides in the dispute have declared a press moratorium during negotiations over this proposal, the labor campaigners have received the proposal gladly and with goodwill. It amounts to a major shift in tone for a dispute that had become a long and bitter standoff.
In recent months, events were developing in favor of the union cause.
First, the ''Litton campaign'' grew to include 12 labor unions, including the AFL-CIO's Industrial Union Department. This gave final momentum to a year and a half of rallies across the US.
In November, a bill cleared a US House subcommittee that would bar repeat violators of labor law from winning government contracts, moving it closer to consideration by the full House.
The bill has been introduced before as part of a labor-law reform package that passed the House only to be filibustered in the Senate. But labor advocates have higher hopes for this bill, now that it is on its own.
About $1.3 billion - a third of Litton's revenues last year - came from government contract work.
Most important, the National Labor Relations Board has - in the last six weeks - set up a special unit for handling charges against Litton. And instead of reviewing charges against Litton divisions separately, the NLRB is reviewing the patterns of alleged violations throughout the conglomerate on the suspicion that Litton labor practices are directed from the home office in Beverly Hills.
Litton has consistently denied that its labor practices are centrally directed.
Of about 50 complaints the NLRB has issued against Litton in the past two decades, just under half have been decided against the company. A dozen more have been settled with Litton paying damages or relief.
The ''Litton Campaign'' was launched in 1980 at a microwave oven plant Litton had moved from Minneapolis to Sioux Falls, S.D. The United Electrical, Radio, and Machine Workers won an election there, but claims that the company has not bargained in good faith since.
The campaign charges against Litton include plant closings, runaway shops, and union busting. Litton's O'Green has called the charges ''inaccurate, without foundation, and patently wrong.''