The breakaway of 120,000 Canadian members from the United Automobile Workers is the first major defection by nationalistic trade unionists from their United States-based international, and one that will be watched closely on both sides of the border.
Although the break surprised some because it happened so suddenly at a Dec. 10 UAW board meeting, it was not totally unexpected. The dispute between the UAW and its Canadian workers had been building for five years.
A year after Robert White became director of the UAW in Canada in 1978, the district balked at, but later supported UAW concessions to the Chrysler Corporation, then facing bankruptcy.
Two months ago, differences between UAW's leaders in Detroit and the Canadians became critical when, in separate bargaining with General Motors, Mr. White led Canadian auto workers in a 23-day strike to force contract terms that met Canadian needs rather than following the US contract pattern.
The walkout forced the closing of 23 US plants and idled more than 40,000 US workers. It was widely unpopular among auto unionists in this country.
After the strike, Canadian leaders said the UAW leadership in Detroit tried to exert pressure for a settlement similar to the US agreement. UAW president Owen Bieber denies the charge.
On Dec. 10, Mr. White, the lone Canadian executive board member, confronted US members with a demand for autonomy for his district. The main issue was the Canadian right to negotiate and strike independently of the parent union. Mr. White also demanded other things including control of Canadian staff members and dues paid by Canadian auto unionists. The demands were voted down 24 to 1.
Afterward, Mr. Bieber of UAW and Mr. White called the break amicable and said that when it becomes official the UAW and the new Canadian Auto Workers will have ''close fraternal ties.'' The Canadians will remain a part of the UAW for the present.
In coming years the defection could make auto bargaining more difficult. Canadian financial analysts fear an emergence of a more militant union movement that could slow industrial investment in the country.
The break will reduce the UAW's membership to below 1 million and cut its dues income. The union's influence in the US would not be seriously hurt.
In Canada, the CAW should be financially solid and very likely more militant with employers and in politics.