Samsung infringed Apple patents to make its smartphones and tablets, a U.S. trade panel judge said in a preliminary decision issued on Wednesday.
Apple had filed a complaint in mid-2011, accusing Samsung of infringing its patents in making its Captivate, Transform and Fascinate smartphones, as well as the Galaxy Tablet.
Judge Thomas Pender said Samsung infringed four Apple patents but did not violate two others listed in the complaint. There had been seven listed initially, but one was dropped during litigation.
The full International Trade Commission will decide in February whether to uphold or reject the judge's decision.
Samsung was found to infringe an Apple patent that helps the touchscreen interpret whether the user wants, for example, to scroll up and down or switch between applications. It was also found to have infringed a patent that allows the device to show an image on a screen with a second, translucent image over it.
Patent battles between Apple and Samsung have taken place in some 10 countries as they vie for market share in the booming mobile industry.
Apple has asked a federal court in California and the ITC to permanently ban Samsung products that infringe Apple patents. Neither the judge nor the ITC has ruled on the issue.
Earlier on Wednesday, a Dutch court ruled that Samsung did not infringe Apple patents by using certain multi-touch techniques on some of the Samsung Galaxy smartphones and tablet computers.
Apple scored a sweeping legal victory over Samsung in August when a U.S. jury found Samsung had copied critical features of the popular iPhone and iPad and awarded Apple $US1.05 billion in damages. Samsung has appealed that verdict.
Google's Android software, which Apple's late founder Steve Jobs denounced as a "stolen product," has become the world's No.1 smartphone operating system. Apple's legal battle against it has dragged in hardware vendors who use it, including Samsung and HTC.