Despite changes in patent law expected to curb the filing of lawsuits by nonpracticing entities, NPE litigation increased significantly in 2015.

A new study by RPX Corp., which helps companies reduce the cost and risk associated with NPE litigation, reports that NPEs filed 3,604 cases last year, almost 25 percent more than the 2,891 cases filed in 2014 and slightly less than the 3,733 filed in 2013.

IP practitioners believed that moves by Congress, the U.S. Supreme Court and the U.S. Patent and Trademark Office taken in recent years would help reduce the number of patent suits filed by NPEs, especially those filed by so-called patent trolls, companies that buy up patents and assert them in order to extract settlements.