A U.S. District Court judge ruled here yesterday that British airline entrepreneur Freddie Laker may have his antitrust suit heard in the American court system, rejecting arguments by some of the airlines Laker is suing that the case should be heard only in the British courts.

In the most significant ruling to date in the case, Judge Harold H. Greene rejected the airlines' claims that the Laker case belongs in the British court system because Laker is a British national and his defunct airline was a British corporation. Attorneys for Laker had argued that the airlines wanted the case heard in the British system because U.S. antitrust laws are more stringent than those of Great Britain.

Laker, who ran the no-frills "Skytrain" flights between the United States and Great Britain until his airline went out of business in February 1982, is alleging that eight airlines--British Airways, British Caledonian, Pan American, TWA, Sabena, Swiss Air, Lufthansa and KLM--as well as McDonnell Douglas Corp. and McDonnell Douglas Finance Corp., conspired to undercut his low rates and deliberately drove him out of business.

After Laker filed his antitrust suit in federal court here, British Airways, British Caledonian, Swiss Air and Lufthansa filed countersuits in the High Court of Justice in England to prevent Laker from continuing his court action in the United States.

The British court subsequently enjoined Laker from taking any further steps against British Airways and British Caledonian in the U.S. courts and is scheduled to decide the Swiss Air and Lufthansa actions later.

Yesterday's ruling effectively prevents KLM, Sabena and the American airlines from joining suits now pending against Laker in the British courts and from initiating any actions of their own against Laker outside the United States.

In his opinion, Judge Greene called "unprecedented" the level to which the British court has involved itself in Laker's U.S. litigation, noting "the British court apparently intends to decide issues of American antitrust law as well as of British law."

Greene noted in his opinion that a major difference between American and British antitrust law is that it is not illegal under British law for corporations to drive a competitor out of business if the corporations are acting in their own self-interest. Greene says that corporations who do not want to be held to U.S. antitrust laws "should not do business here."

Laker attorney Carl Schwarz said Greene's decision "breaks new ground" in the area of court jurisdiction.

Fred D. Turnage, attorney for Pan American, called Greene's decision "far-reaching," but said that Pan American had "not yet determined what course of action, if any to take."