These days, patent disputes among technology companies are common, particularly among those that create handheld devices. But smartphone and tablet makers are increasingly trying to conquer their rivals in another way: by accusing competitors of violating antitrust laws.

The Wall Street Journal reports that many mobile device manufacturers are asking the Department of Justice (DOJ) to investigate rival tech companies that are allegedly breaking antitrust laws.

In an Oct. 17 letter to Gene Kimmelman, the DOJ's chief counsel for competition policy, Barnes & Noble Inc. accused Microsoft Corp. of monopolizing the mobile device market by demanding patent royalties on devices running on Google Inc.'s Android operating system.

“Microsoft is attempting to raise its rivals' costs in order to drive out competition and to deter innovation in mobile devices,” wrote Barnes & Noble.

The letter was in response to Microsoft's complaint against Barnes & Noble with the International Trade Commission, in which the software maker alleges that the retailer's Nook reader infringes five patents. The trial is scheduled for February 2012, according to Bloomberg.

The Wall Street Journal reports that in the past few months, companies such as Apple Inc., Google, Microsoft and Samsung Electronics Co. have visited the DOJ, claiming their competitors are violating antitrust laws.

But some experts familiar with the matter worry that if the DOJ limits how technology companies can brandish their patents, it could discourage innovation.

Read the Wall Street Journal for more on this story.