The Supreme Court opened its 1988-89 term Monday, announcing it is widening its already broad review of drug testing provisions that have been enacted by government and private industry across the country.

The court, beginning its term on the traditional first Monday in October, agreed to decide if Conrail can test its employees for drug and alcohol use during company physical examinations without first negotiating the tests with railway labor unions.The court will hear arguments this term in the case brought by Conrail seeking review of a ruling by the 3rd U.S. Circuit Court of Appeals.

The case before the court involves a Conrail rule, announced Feb. 20, 1987, that it would include a drug screen as part of urinalysis in all periodic examinations. The unions challenged the rule, arguing it cannot be unilaterally imposed and must instead be negotiated. A lower court disagreed but the appeals court reversed.

The court's action brings to three the number of drug testing cases it will review. The other two cases, which are scheduled to be argued Nov. 2, deal with requiring drug testing of railway workers involved in accidents and a mandatory drug testing program of certain Customs Service workers.

Nationwide, drug testing in the workplace in becoming more common and has the broad backing of the Reagan administration.

The legal questions about such programs concern mainly government employers and heavily regulated industries. Monday's case would have broad ramifications for private employers that have collective bargaining agreements.

The court has never ruled on the constitutionality of drug testing programs and lower courts have split on the issue, and the high court's final action should have great symbolic value. If the court approves drug testing, it would likely accelerate the rush to drug testing.

In other action, the justices:

-In a major church-state case, agreed to decide whether Pittsburgh area officials may place a nativity scene and Jewish menorah in city and county buildings during the Christmas and Chanukah seasons.

-Agreed to hear an appeal by the city of Dallas of a lower court ruling striking down an ordinance that set up special dance halls exclusively for teenagers.

-Stepping into a major antitrust dispute, agreed to decide to what extent states may recover costs passed on to them in illegal price-fixing conspiracies.

-Rejected a challenge by California Republicans who were seeking to prove that congressional district lines drawn by the Democratic legislature were an unconstitutional gerrymander.

Other rulings Monday:

-The court left intact a $48.3 million judgment awarded Trans World Airlines against a company founded by the late billionaire Howard Hughes. It rejected arguments by Summa Corp. and William R. Lummis, administrator of the Hughes estate, that the award should be thrown out.

-The justices rejected a challenge to the rates being charged for transporting oil through the Trans-Alaska Pipeline. Without comment, The justices, left intact a rate agreement between Alaska and the pipeline's eight owners. The rates were challenged by the Artic Slope Regional Corp., established under Alaska law to protect the rights of Inupiat Eskimos.

-The justices, without comment, let stand Nevada court decisions dismissing Sherri Spil-lane's lawsuit contesting the $18,000 settlement she received in 1983 from Mickey Spil-lane, creator of the fictional detective Mike Hammer.

One state judge noted that the former Mrs. Spillane obtained a marriage license to marry Michael Standing 20 minutes after her divorce from Spillane was final. The judge said that while still married to Spillane, Sherri Spillane had a longterm love affair with Standing.

"The court will not pass judgment on morality, but such actions certainly are not those of a caring, faithful, loving spouse," the judge said.