A District Court judge in Delaware has ruled that Acushnet has to stop selling its Titleist Pro V1 family of golf balls, which Callaway Golf said infringed on four of its patents. Following the deliberation of a jury last December, the court issued a permanent injunction on the sale of these balls last week. Acushnet point out that the ruling only applies to sales of the balls in the USA and said it has appealed the U.S. court’s verdict.

The injunction in the USA is set to start no later than Jan. 1, as Callaway requested that professional golfers be allowed to play with the Pro V1 balls through the end of the year. The court turned down Acushnet’s request that the jury’s verdict be overturned.

Damages have not been decided in the case, but the Pro V1 has been hugely successful since its introduction in October 2000, selling more than $1 billion worth of balls. If the court decides that the patents were critical in the ball’s success, an award of $50 million would not be out of the question, and some say it could even reach $100 million. The technology gives the ball the distance of a hard cover but the feel of a soft cover.

Acushnet, which is owned by Fortune Brands, points out that it converted the production of the balls in September so they would be “outside the scope of the patents in question.” It plans to offer a new Pro V1 ball in the first quarter of next year. In June, the U.S. Patent and Trademark Office moved one of the four patents to the appeal stage and ruled another one invalid.

Acushnet says the injunction will have no effect on its financial results. It pointed out that it holds more than 650 active patents on golf balls. More than 65 are related to the Pro V1 products.