Organized labor is hailing a court victory over the Reagan administration in a construction wage case as ''a fine victory'' - a victory that confirms labor's view that the administration has overstepped its authority to amend federal law.
The US Labor Department July 22 was restrained by federal court order from changing the Davis-Bacon Act - the ''prevailing wage law'' covering federally funded construction work. The 1931 law has been a target of unsuccessful legislative attacks throughout most of its history.
Davis-Bacon modifications ordered by Labor Secretary Raymond Donovan - estimated to save federal contractors $600 million a year - were scheduled to go into effect July 27.
The current restraining order against the changes is temporary, but AFL-CIO's Building and Construction Trades Department, which brought the court action, expects the bar to become permanent.
Until the Labor Department proposed its new regulations, Judge Harold Greene noted, the prevailing wage law (as enacted in 1931 and amended in 1935) remained unchanged under eight presidents and 15 secretaries of labor. Such a consistent administration of the law ''must be accorded very substantial weight by the court,'' he said.
He added that the purpose of the act is to protect wages of construction workers ''even if the effect is to increase the costs of construction to the federal government.''
The Labor Department has said that as many as 600,000 contracts are subject to Davis-Bacon and that $43 billion is spent each year for federal construction projects. Government critics have called the prevailing-wage requirement inflationary, and the construction industry calls it oppressive and unnecessary.