The US International Trade Commission on Friday ruled that South Korea's Samsung infringes on portions of two Apple Inc patents on digital mobile devices, covering the detection of headphone jacks and operation of touchscreens.
The decision is likely to inflame passions in the long-running dispute and could spark a rebuke from South Korea.
The panel moved to prohibit Samsung from importing, selling and distributing devices in the United States that infringe on certain claims on the patents. It is unclear how many Samsung phones and devices would be subject to the ban.
All exclusion orders are sent to President Barack Obama, who has 60 days to review them. If he does not veto the order, it will go into effect.
Apple was ebullient. "The ITC has joined courts around the world in Japan, Korea, Germany, Netherlands and California by standing up for innovation and rejecting Samsung's blatant copying of Apple's products," said company spokewoman Kristin Huguet.
The ruling was the latest in a patent battle between Apple and Samsung that has spread across several countries as the companies vie for market share in the lucrative mobile industry. Samsung and Apple are the Nos. 1 and 2 smartphone makers.
But it comes less than a week after the Obama administration overturned an ITC decision from June that would have banned the sales of some older-model Apple iPhones and iPads in the United States for violating Samsung patents.
US Trade Representative Michael Froman vetoed the ban on Saturday, cited its "effect on competitive conditions in the US economy and the effect on US consumers."
That move, the first veto of an ITC ruling in decades, triggered concerns in the South Korean government and led to closer scrutiny of Friday's ruling than usual.
Letting the ban on Samsung devices stand after having so recently intervened in the Apple case could spur allegations the administration is showing favoritism toward Cupertino, California's Apple.
But a key difference between the cases is that the patents Apple was said to have infringed were so-called standard essential patents, which cover technology that must be used to comply with industry standards. The patents in the latest case are considered commercial and non-essential.
Four other patent infringements asserted by Apple were turned down on Friday by the ITC panel, which declared its investigation closed.
"We are disappointed that the ITC has issued an exclusion order based on two of Apple's patents. However, Apple has been stopped from trying to use its overbroad design patents to achieve a monopoly on rectangles and rounded corners," Adam Yates, a Samsung spokesman, said in a statement.
Apple had filed a complaint in mid-2011, accusing Samsung of infringing its patents in making a wide range of smartphones and tablet. Apple has alleged that Samsung's Nexus 4G and some Galaxy and Intercept devices were among those made with the infringing technology.
Samsung has said its newer models incorporate features that work around disputed technology.
In a busy day in the long-running series of patent spats by the two archrivals, a US appeals court earlier on wrestled with a request by Apple for a permanent injunction on sales of some phones made by Samsung for other alleged violations.
Apple is appealing a lower court ruling that rejected the iPhone maker's request that some older-model Samsung phones be permanently banned.
At stake is whether judges can permanently ban the sale of a complex device like a smartphone if a court finds that it violates a patent that covers just one of the device's hundreds of features. Samsung and other smartphone makers say a decision in favor of Apple could cripple the market.
At an hour-long hearing in Washington, US Federal Circuit Court of Appeals Judge William Bryson questioned whether Apple wanted to use the appeal to set a precedent that would allow it to seek sales bans for newer Samsung phones in an expedited fashion.
The current case has dragged on for two years.
Apple lawyer William Lee acknowledged that if the iPhone maker's injunction request was granted, the company would seek a so-called contempt proceeding to go after newer Samsung phones.
Samsung's popular Galaxy smartphones and tablets run on Google's Android operating system, which Apple's late co-founder, Steve Jobs, once denounced as a "stolen product."
Apple says Samsung has infringed its patents and caused financial losses. Samsung denies it copied Apple's patented features.
The appeals court is expected to issue a written opinion but did not indicate a timeline.
The case is Apple Inc v. Samsung Electronics Co Ltd, Federal US Circuit Court of Appeals, No. 13-1129.