The US International Trade Commission blocked imports of some older model Samsung mobile devices following complaints by Apple that the South Korean company had violated its patents.
The ruling by the Washington-based trade body was the latest in a long-running and bitter global battle over alleged patent infringement between the two smartphone and tablet computer giants.
The ITC ruled that Samsung had infringed two Apple patents—numbers 949 and 501, dealing with touchscreen actions and headphone jack plug-ins—but cleared the South Korean company of charges that it had violated four more.
Apple welcomed the ITC ruling while Samsung expressed its disappointment.
"With today's decision, 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," Apple said in a statement.
"Protecting real innovation is what the patent system should be about," it said.
Spokesman Adam Yates said Samsung is "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," Yates said, referring to design features at issue in rejected patent claims.
"The proper focus for the smartphone industry is not a global war in the courts, but fair competition in the marketplace.
"Samsung will continue to launch many innovative products and we have already taken measures to ensure that all our products will continue to be available in the United States," the Samsung spokesman said.
It was unclear precisely which devices would be targeted in the ban, but it was aimed at early model smartphones and tablets that are no longer hot products in the United States.
"It really doesn't mean that much," independent Silicon Valley analyst Rob Enderle said of the ITC ruling.
"It is not the new stuff they are talking about, but the older devices that are more likely to be shipped to emerging markets than here."
The import block is subject to a review by the White House and Samsung will be allowed to continue to sell the items at issue during the two-month review period.
The ITC ruling raised the question of whether US President Barack Obama's administration will once again intervene in a patent fight playing out between the companies at the agency.
Less than a week ago, the US Trade Representative overturned an ITC ruling in a patent suit brought by Samsung against Apple that would have banned the sale of certain iPads and iPhones in the United States.
It was the first time the USTR has overruled the commission since 1987, and South Korea's trade ministry made its feelings clear at the time.
Legal analysts point out that a critical difference in the cases is that the USTR intervened regarding patents deemed "standards essential," indicating that the technology involved was needed to comply with industry standards.
"Our ministry expresses concern about negative impacts the decision by the USTR will have on protecting patents held by Samsung," the company said in a statement at the time.
The ITC ruling also opens a door for Apple to try to use the same patent violation claim against newer Samsung gadgets that have incorporated the same technology.
Samsung has taken pains to modify smartphone and tablet designs to avoid attacks over Apple patents.
"I don't think this decision will reverberate much through Samsung's product line," Enderle said.
In a separate battle in US federal court, Samsung was ordered last August to pay more than $1 billion for patent infringement, a ruling which also opens the door to a ban on some Samsung devices.
A judge later slashed the award to $598.9 million. Apple continues its quest to get other Samsung mobile devices banned in that case.
Legal brawls between Samsung and Apple became common after the South Korean company began gobbling smartphone market share with devices powered by Google's free Android operating system.
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