A man looks at his Apple iPad in front outside an Apple store in downtown Shanghai. The third-generation iPad has faster chips, fourth-generation wireless, a sharper display and a better camera. Reuters/Aly Song
A judge at the US International Trade Commission, a quasi-judicial agency which
investigates trade complaints, found "no violation" by Apple of the patents for wireless communication devices and tablet computers, said a statement on the preliminary ruling.
The ruling by administrative judge James Gildea is subject to review by the full commission.
It was the latest victory for Silicon Valley-based Apple, which last month won a massive patent lawsuit against Samsung in a California court, which ordered Samsung to pay more than $1 billion for patent infringement.
Samsung however said it remained "confident" that the full commission would decide in its favor, ruling that "Apple must be held accountable for free-riding on our technological innovations."
"We are proud of our long history of innovation in the mobile industry and will continue to defend our intellectual property rights," the company said in a statement.
A series of legal battles are pending around the world, including claims by Samsung that Apple illegally used the South Korean electronics firm's wireless communications technology.
The ITC has the authority to ban imports of devices if it finds patent infringement.
Florian Mueller, a patent consultant who follows technology issues, said the case was another setback for the South Korean giant.
"Samsung was hoping (and despite today's setback will continue to hope) to gain some leverage over Apple from an ITC import ban," he wrote in a blog post.
"And in light of the recent California trial, Samsung needs leverage sooner rather than later."
The judge in the California Apple-Samsung case set a December 6 hearing on punitive damages to the US firm for patent infringement and on whether to ban eight Samsung phones in the US market.
Apple has asked the court to ban some of the newer 4G phones from Samsung's Galaxy line in the case.
Samsung has said it would appeal and has pledged to fight the proposed ban.