As of October 31, 2011, U.S. Reissue Patent No. RE 37,516 has been declared invalid and unenforceable. The District Court for the Eastern District of Pennsylvania ruled that RE 37,516 was invalid because it: (1) was on sale more than one year prior to the date of the application in violation of 35 U.S.C. section 102(b); (2) was actually invented by someone else (the French company Laboratoire L. Lafon); (3) was obvious at the time the invention was made to a person having ordinary skill in the art under 35 U.S.C. section 103(a); and (4) failed the written description requirement of 35 U.S.C. section 112. The patent was also found to be unenforceable due to Cephalon's inequitable conduct during patent prosecution.