In yesterday's final determination, the ITC said that HTC violated Section 337 of the Tariff Act by importing and selling phones that infringed two claims of Apple's US patent 5,946,647.
The patent is titled "System and method for performing an action on a structure in computer-generated data" and covers technology allowing users to perform tasks such as calling a phone number or adding a calendar appointment with a single finger tap on the screen.
HTC has until April 19 to comply with the ruling. This is to provide "a transition period for US carriers" said the Commission. It can also import refurbished handsets until December 19 2013 for replacements under warranty.
Despite that finding, the decision was generally good news for the Taiwanese company, which makes smartphones that run Google's Android operating system.
The ITC reversed a preliminary finding that HTC had also infringed two further claims of the '647 patent and another patent, 6,343,263 for a "Real-time signal processing system for serially transmitted data".
It also upheld a finding that two further US patents, 5,481,721 and 6,275,983, were not infringed.
In a statement, HTC's general counsel Grace Lei said: "We are very pleased with the determination and we respect it."
Apple brought the case before the ITC in April 2010. Several of the patents at issue in the case had also been asserted against Nokia, but that dispute was settled earlier this year.
The ITC case is one of many disputes between Apple and other smartphone makers, many of whom use Android. Apple and HTC have a number of other suits pending against each other in the ITC and in federal courts.
For more on the smartphone patent wars, see Managing IP's dedicated topic page.