DALLAS (AP) _ An appeals court has ruled that Upjohn Co. may withhold data on Halcion from the public but still show records of clinical tests to the jury considering a man's claim that the sleeping pill drove him to kill.

Monday's decision by the 5th District Court of Appeals in Dallas overturns a ruling by Judge John Marshall, who is presiding over the first civil trial involving the controversial drug.

William R. Freeman, his wife and four children are suing Kalamazoo, Mich.- based Upjohn for $5.5 million, alleging that the drug altered his personality and caused him to murder his best friend in 1987.

Freeman, formerly assistant chief of the Fort Stockton police department, is serving a life prison term for Donnie Hazelwood's murder.

The trial against Upjohn began Oct. 5 but was recessed Monday. It is scheduled to resume Oct. 20.

Marshall had ruled that records documenting clinical tests of Halcion should not be barred from the public once they are introduced into evidence during the trial. Freeman's attorneys, who obtained the documents during discovery, plan to introduce them.

Upjohn appealed immediately, asking for a temporary order pending a full hearing on the matter scheduled for Nov. 9.

The appeals court's two-page opinion, written by Judge James Baker, says the documents may be disclosed only to the attorneys involved, their expert witnesses, Marshall and jurors.

Attorneys for The Dallas Morning News and the consumer group Public Citizen, which have been fighting to keep the records public, said they would appeal the opinion to the Texas Supreme Court.

Mike Mosher, an attorney for Freeman, said he intends to show the records on a courtroom wall using an overhead projector. He also might ask witnesses to read aloud from some of the documents during the trial, which is open to the public.

Upjohn attorney Earl B. Austin of Dallas would not say whether the company would object to those tactics.

''We just intend to try this case under the normal rules,'' he said. ''If the other side is dwelling on reading the documents, then we might have to do something about that.''

Austin said the way Upjohn conducts its clinical trials is considered a trade secret, and the drugmaker would be harmed financially if the records were made public.