As the world changes, courts are always being handed novel issues that arise from new technology or new social patterns. But sometimes judges have to grapple with an issue that is new simply because it has never come up before, even though the facts and the legal theories behind it have been common for centuries.

That is what happened recently in a case in which an injured seaman sued the shipping line for which he worked. The controversy forced the U.S. Court of Appeals in New York to make the first pronouncement ever in federal courts about the extent of a judge's power to use the relatively obscure legal device of "remittitur."

But along the way, the appellate panel made important new law that may affect a whole range of damage cases.

"Remittitur" -- like its opposite, "additur" -- essentially lets a judge offer a deal to the winning litigants in a civil damage case. It comes up in situations where a jury, in the judge's view, has gone a little crazy and returned an award that is grossly out of proportion to what would be a fair settlement in the dispute.

In such cases, the judge had the power to wipe the slate clean and order a new trial. But he can offer an alternative: keeping the jury's conclusion, but changing the dollar amount of the award. If the judge tries to reduce the award, that's a "remittitur"; if he or she tries to increase the amount, it is an "additur."

In 1935, the U.S. Supreme Court by a 5 to 4 vote said that federal judges could not offer an additur, but that a remittitur is okay, although to be used sparingly. Usually the judge simply offers a reduced dollar amount, but in the recent seaman's case, the arithmetic was worked a bit differently.

The dispute was over an accident that happened in 1977 when Carl O. Akermanis, then 59 and a third assistant engineer on the Sea-Land Service's S/S Los Angeles, slipped during choppy weather while working to remove some rusted hardware from the ship's deck.

Akermanis and the line disagreed about virtually every fact surrounding the incident and its aftermath, but the jury mostly believed Akermanis.

The members decided that he suffered damages totaling $528,000, and that, while Sea-Land was mostly to blame, the engineer had himself not been as careful as he should have been. He contributed 4 percent to the cause of the accident, they decided, so the award would work out to $21,120 less than the actual damages.

Judge Charles S. Haight Jr. ruled that the 4 percent figure was unreasonable; he found that Akermanis, because he had the freedom to schedule his on-deck work at times when the sea was calmer, contributed at least 25 percent to the accident. Accept $396,000, or face a new trial, he told Akermanis. Akermanis took the deal.

But Sea-Land objected, and took the issue to the Court of Appeals. The judges there, after searching the law books and deciding that there had never been such a case in federal court, ruled that Judge Haight had overstepped his authority.

Admittedly, the end result of his action is to reduce the amount of the award, they said, but nonetheless what he had done was raise a figure -- the amount the seaman contributed to the accident -- and as they read the 1935 Supreme Court precedent, all a judge can do is lower a jury finding. So the deal was overruled, and Haight was told to reconsider.

But Haight had found nothing wrong with the way the jury had figured the total amount of damages suffered by Akermanis, only with the way the blame was apportioned. So he had ruled that if there were a new trial, it would be only about apportioning liability; the dollar figure decision would be carried over from the first trial and not left up to the second jury.

That is a most unusual procedure, one that the Supreme Court as long ago as 1915 said would rarely be proper. But the appellate judges said that because the trial judge was convinced that the jury had reached a reasonable conclusion on the total value of Akermanis' suffering, it is all right not to try that part of the case again.

Even if the case of the accident on the deck of the S/S Los Angeles never gets before a jury again, that ruling on a second trial is likely to be important.

Joseph T. Stearns, Sea-Land's lawyer in the case, thinks that it will lead to more litigation. Before, in a situation like the Akermanis case, where a jury came in with a higher damage award than the defendant expected and the case was ordered back to trial, the parties would usually settle. The defendant would figure that the second result might not be as lucky. But with the dollar figure set, there are fewer variables at play in the second case, and so less pressure to settle.

But the irony is that the major new holding on the scope of a retrial would never have come had not a fresh question of law -- the proper bounds of the remittitur device -- gotten the controversy into the Court of Appeals in the first place.