The Supreme Court let stand yesterday a ruling that a reporter can be subpoenaed and questioned about confidential conversations with news sources by a litigant in a civil suit in which she and her publisher are not involved.

The case involves stories in the Des-Moines Register and Tribune in January 1975 about litigation by Sally Ann Winegard, 33, to dissolve her common-law marriage with John R. Winegard, 56, a Burlington, Iowa, millionaire. Iowa courtshave upheld the marriage as valid.

The prevent her from discovering financial information about him, Winegard filed an action in U.S. District Court that eventually was dismissed as "frivolous." In the process, he filed papers bearing on his wealth.

After reviewing the federal court records and making some inquireies, reported Diane Graham wrote the stories at issue.

She reported that "Mrs. Winegard's attorney, Stephen Schalk of Davenport, said the two exchanged wedding rings during a return flight from Las Vegas in 1971 and have held themselves out to the community as husband and wife since that time."

The stories also said that "according to the attorney," a daughter from one of Mrs. Winegard's previous marriages had her last name changed to Winegard, and, that "John and Sally Ann have continued living together for more than two years since she filed the original dissolution of marriage papers."

Winegard then sued Scholk's law firm for invasion of privacy. The First Amendement issue arose when Schalk, replying to a pretrial written request for admissions, acknowledged having talked to Graham, but denied being the source of the statments she had attributed to him.

With that, Winegard subpoenaed Graham and the Des Moines Register and Tribune Co. to testify. She said that she "substantially wrote" the articles and that they were true and correct to the best of her knowledge. But she and the company refused to answer more than 100 questions about converstions with or the identity of her sources, preparation of the stories, or editing procedures.

The publisher and the reporter then launched a court action of their own to quash the subpoenas: Wineguard countered with a motion to compel them to give depositions.

Judge Leo Oxberger ruled for the reporter and her publisher, holding that under the First Amendment, she had a "qualified privilege" under which she did not have to testify.

Last October, in the ruling allowed to stand yesterday, the Iowa Supreme Court reversed. It agreed that Graham had a qualified privilege, but said it was overridden by the "compelling state interest" in giving civil litigants access to any person's evidence.

The opinion said that Graham was apparently the only person who could say whether Schalk had made the statements attributed to him. But the Register and Tribune, in a U.S. Supreme Court brief, said that Winegard at no time had tried "to depose any member" of Schalk's law firm.

Beyond that, the company said that the "vague and unworkable" standard set in Iowa "leaves no room for protection of delicate First Amendment rights.

The cout took First Amendment actions:

In a Newark, N. J. case , the court let stand a ruling nu the 3rd U.S. Circuit Court of Appeals that the police department improperly denied freedom of speech with a regulation that orders officers not to publicly disparage or comment unfavorably of disrespectfully on the official action of a superior." The department enforced the order against officers who critized handling of a tense racial dispute.

In a Housten case, the court let stand a ruling that free speech didn't protect bill-collector Stella Thorton against a conviction for harrassing at his office, a purported debtor with as many as three telephone calls in a single five-minute period.

In a Waterbury, Conn., case the court let stand a breach-of-the-peace conviction of a ticket-seller in a rock concert theater who greeted plain-clothesman who rad indentified themselves as narcotics detectives with a sexually explicit word, "No . . .'narks' are coming in here," said Pasquale Teporale.