A U.S. District Court jury has ordered the American Broadcasting Companies Inc. to pay $200,000 in damages to a Washington-based free-lance writer, after finding that the company failed to give him on-air credit for television broadcasts based on his article about former president Jimmy Carter.

Peter Peckarsky, an attorney and free-lance journalist, charged in a 1981 civil suit that ABC failed to honor agreements to pay him and give him on-air credit for broadcasts based on an article he wrote about Carter's personal and campaign finances. There were at least nine such broadcasts on ABC's "World News Tonight" and "Good Morning America" in 1978, according to Peckarsky's lawyer, Alan L. Melamed.

During a week-long trial before Judge Harold Greene, Melamed charged that ABC breached its contract with Peckarsky and "fraudulently misrepresented" to him that he would get on-air credit.

ABC's attorney denied a breach of contract and argued that the official whom Peckarsky dealt with made it clear throughout their negotiations that he had no authority to bind the company to on-air credits. The official, C. Robert Velnick, then director of news coverage in ABC's Washington bureau, was also named in the lawsuit as a defendant.

The jury late Wednesday found that there had been no breach of contract. But it awarded damages to Peckarsky on the claim of fraudulent misrepresentation.

Peckarsky said yesterday, "I am happy, not only for myself, but also for what this case may do to protect the rights of other free-lancers."

Melamed had argued in court that the on-air credit would have enhanced Peckarsky's reputation and possibly advanced his career.

Both sides agreed that Peckarsky was paid $500 a week for three weeks in August 1978 as a free-lance reporter for ABC and $2,000 for two broadcasts based on his article, according to lawyers in the case.

However, Peckarsky's lawyer contended that several further broadcasts were based on his article. In contrast, ABC, according to documents filed in court, contended that the other broadcasts merely reported reaction to the allegations in ABC's initial broadcast.

ABC's attorney, Michael Calvey, said yesterday that he will ask the judge to set aside the jury's verdict in the case or to grant his client a new trial.