In a mixed ruling the International Trade Commission (ITC) found that Samsung had unfairly used Apple technology in some of its devices. It issued cease and desist orders banning further imports of some Samsung products. But the ITC dismissed four other claims made by Apple.
The verdict came as Apple asked an appeal court to force Samsung to stop using iPhone features that a jury had declared to be in violation its patents.
In the latest salvoes in the long running battle between the world's top two smartphone manufacturers, Apple is seeking to overturn a court order that allows Samsung to continue to sell products that use the disputed patents.
William Lee, of the law firm WilmerHale, told the US court of appeals in Washington: "Apple spent five years and $5bn to develop a product and it was a revolutionary product. Samsung said: 'We can copy it easily.' They spent three months to bring a product to market."
Samsung lawyer Kathleen Sullivan argued that monetary compensation would be an adequate remedy for any infringement.
Samsung has disputed the patent infringements and Apple's claims that it has suffered material losses as a result of the breaches. But last year a California jury found against the South Korean company and awarded Apple more than $1bn in compensation. The jury ruled that 26 of Samsung's products violated six Apple patents. Judge Lucy Koh later denied Apple's request to ban the sale of the products found to be in breach. Koh ruled that Apple had failed to show any harm it may have suffered in the market was due to Samsung's infringement.
The dispute comes at a difficult moment for Apple, which is losing market share to smartphones using Google's Android operating system, many of which are made by Samsung. According to IDC, Apple's share in the worldwide smartphone operating system market fell in the second quarter of 2013 compared to the same quarter last year. Android and Microsoft's Windows Phone both increased market share.
In court on Friday, Samsung's lawyers argued that Apple had not shown a "causal nexus" linking the sales dip to patent infringement. Some 23 of the 26 disputed products have also now been withdrawn from the market. The appeals court is not expected to rule on its case until the autumn.
In June the ITC ruled that Apple had infringed some of Samsung's patents and banned imports of some older iPhone and iPad models made to run on AT&T and T-Mobile USA networks. Last week the Obama administration overturned that ban.
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