Twitter said on Tuesday that it would structure its patents so they could not be used for offensive litigation purposes without permission from the people who developed them.

Twitter said the move would give inventors more control over their creations and ensure its patents are not used to impede the innovation of others, the company said in a post on its official blog.

It is a commitment from Twitter to our employees that patents can only be used for defensive purposes. We will not use the patents from employees' inventions in offensive litigation without their permission, Twitter said on the blog.

Twitter, which launched its microblogging service in 2006, does not currently have any patents, but sources said the company has applied for many.

Patent litigation involving tech companies has exploded during the past two years. Yahoo Inc sued Facebook in March for infringing ten of its patents, and smartphone manufacturers such as Apple Inc and Microsoft Corp are engaged in a fierce legal war against rivals such as Motorola Mobility.

Some patent holders are derided as patent trolls by critics, a term the holders say unfairly paints them as villains for helping inventors make money.

Twitter said that the limits on the use of its patents, which it dubbed the Innovator's Patent Agreement, will apply to patents even after they are sold.

Eric Goldman, an associate professor at Santa Clara University School of Law, said Twitter's announcement will burnish the company's standing among software engineers, some of whom have grumbled at seeing their patents used to sue other companies.

Unquestionably, it's an effort to define Twitter's brand in the marketplace and to signal that its perhaps more engineering-friendly than companies that wouldn't make such a promise, said Goldman.

(Reporting By Alexei Oreskovic; Editing by Leslie Gevirtz)

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