A European Union design Apple Inc. (AAPL) used to win a sales ban on Samsung Electronics Co.’s Galaxy 10.1 tablets may be of limited value after new evidence was introduced in an appeal of the decision, a German court said.

Samsung introduced as evidence a U.S. utility patent using a type of flat screen that was published 13 days before Apple filed its EU design right. That fact may limit the range of protection the world’s most valuable technology company gets, said Wilhelm Berneke, the presiding judge at the hearing in Dusseldorf. Apple may still be able to rely on fair-competition rules for a German ban, he said today, adding that the court’s assessment is preliminary. A ruling is scheduled for Jan. 31.

Under German rules “Apple’s tablet design may have a rather broad range of protection, because it’s widely known,” said Berneke. “But there are also elements that need to remain free, like the feature that tablets are very thin.”

Both sides are appealing a Sept. 9 sales ban issued by a lower court. Samsung (005930) seeks to overturn the ban, while Apple wants it extended to cover all EU countries and both Samsung’s German sales company and the Suwon, South-Korea based parent. The companies are to face each other again on Dec. 22 in the lower court, where Apple is also seeking a sales ban for the Galaxy 10.1N, a tablet Samsung began selling after the Sept. 9 ruling.

The legal battle between Cupertino, California-based Apple and its closest competitor in tablet computers is intensifying as an increasing number of consumers use devices such as tablets and smartphones to surf websites, play games and download music.

As many as 2.1 million tablet computers will be sold in Germany in 2011, a sales increase of 162 percent from 2010, Bitkom, the nation’s technology and telecommunications association, said last week.

The U.S. utility patent and a related German design right published half a year earlier show that the form of design Apple claims as its original invention was already known at the time and thus can’t claim protection, Samsung argues.

Matthias Koch, a lawyer for Apple, told the court those two intellectual property rights were filed for computer screens and can’t be used to prompt design rights for a tablet. The way the objects are used distinguishes both designs, he said.

The U.S. utility patent and the German design right are owned by Bloomberg LP, the parent of Bloomberg News. Bloomberg isn’t a party to the lawsuit.

The court compared devices of several tablet makers to review Apple’s claim that Samsung copied the iPad’s makeup and thus violated German fair-competition rules.

“You can say that tablet designs of all other competitors are farer from the Apple model than Samsung’s are,” Berneke said. “We will have to see whether they come so close that they exploit Apple’s reputation.”

Koch argued that Samsung does because it intentionally designed its tablet in a way to allow its customers to make others believe they own an iPad.

“Samsung’s method is to follow Apple as close as possible,” Koch said. “Their plan is to get a big slice of the cake.”

Apple can seek an EU wide ban only if its design right prevails. Under German fair-competition rules it can only ask for a ban limited to that country.

Today’s cases are: OLG Dusseldorf, I-20 U 175/11 and I-20 U 126/11.