Microsoft began arguing its U.S. trade case that Android-based smartphones made by Motorola Mobility Holdings use technology derived from Microsoft inventions.

In a trial that began Monday before the International Trade Commission in Washington, D.C., Microsoft accused Motorola of infringing seven of its patents and requested a halt to imports of certain Motorola phones. The ITC has the power to stop imports of products that violate U.S. patent rights.

The case is the first smartphone dispute to be heard by the agency since Google said Aug. 15 it would buy Motorola for $12.5 billion to obtain patents that could be used as a bulwark against a surge of lawsuits targeting handsets and tablet computers that use Google's Android operating system.

"We have a responsibility to our employees, customers, partners and shareholders to safeguard our intellectual property," David Howard, Microsoft's corporate vice president and deputy general counsel for litigation, said in an email. "Motorola is infringing our patents and we are confident that the ITC will rule in our favor."

Motorola is "vigorously defending" itself "against Microsoft's patent attack business strategy," Jennifer Erickson, a Motorola spokeswoman, said in an email. "We have also brought legal actions of our own in the U.S. and in Europe to address Microsoft's large scale of infringement of Motorola Mobility's patents."

Microsoft's claim against Libertyville, Ill.-based Motorola is one of more than a dozen smartphone cases before the ITC, as companies seek to use patents to gain a bigger share of a market projected by researcher IHS to reach $206.6 billion this year. Microsoft makes its own mobile operating system, Windows Phone 7, which competes with Android and Apple's iPhone.

The Android platform accounted for 43.3 percent of the smartphone market last quarter, according to research firm Gartner. Microsoft, with less than 2 percent of the market, is counting on an agreement with Nokia to put Windows Mobile on its phones to increase market share.

Cases brought by Microsoft and Cupertino, Calif.-based Apple are targeting devices that run on Android. Microsoft, which contends all Android devices use its technology, also has a case against Barnes & Noble, targeting the Nook reader.

Testimony in Monday's trial focused on details about functions that Microsoft calls "essential to the smartphone user experience," including ways to synchronize email, calendars and contacts; schedule meetings; and notify applications of changes in signal strength and battery power.

Microsoft has asked the agency to block imports of Motorola phones including the Droid 2, Droid X, Cliq XT, Devour, Backflip and Charm. Administrative Law Judge Theodore Essex is scheduled to release his findings Nov. 4, and the commission has a target to complete its investigation by March 5, according to the agency's website.