Earlier today, Tim Lee wrote that two federal district courts — one in Eastern Texas and one in Delaware — account for a growing share of all patent litigation. Here’s one reason why 45 percent of patent holders choose to file suit in those districts: They win more there.

A study of patent lawsuits from 1995 through 2012 by the accounting firm PricewaterhouseCoopers finds that patent holders received damages and/or an injunction almost twice as often in Eastern Texas as elsewhere; Delaware was not far behind.

This was particularly true for "troll" plaintiffs. Non-practicing entities win fewer than a quarter of their cases nationwide. But in East Texas and Delaware, they win more than 40 percent of their cases.

James Bessen does research on technology and innovation at Boston University School of Law. He is the co-author of Patent Failure: How Judges, Bureaucrats, and Lawyers Put Innovators at Risk. You can follow him on Twitter.