The U.S. Department of Justice was clearly concerned about the fate of Research in Motion Ltd., the BlackBerry developer that faced a faced a business-shuttering injunction in 2005. Lawyers for NTP Inc., the company seeking the injunction, knew that. The U.S. government was, after all, the largest single user of BlackBerry devices.

What NTP’s lawyers didn’t know was that Justice had secretly entered into a common-interest agreement with RIM to advance government interests in the patent infringement dispute. Around the time the patent case settled, the attorneys heard about the agreement — and now they want to know more.