In early November 2005 the US Department of Justice filed a brief requesting that RIM's service be allowed to continue because of the large number of BlackBerry users in the US Federal Government.
In January 2006, the US Supreme Court refused to hear RIM's appeal of the holding of liability for patent infringement, and the matter was returned to a lower court. The previously granted injunction preventing all RIM sales in the US and use of the BlackBerry device might have been enforced by the presiding district court judge had the two parties not been able to reach a settlement.
On February 9, 2006, the US Department of Defense (DOD) filed a brief stating that an injunction shutting down the BlackBerry service while excluding government users was unworkable. The DOD also stated that the BlackBerry was crucial for national security given the large number of government users.
9 May 2012 ... RIM's largest single customer, the U.S. Department of Defense, has approved the company-wide use of latest BlackBerry 7 phones.