Former Judiciary Committee chairmen Jim Sensenbrenner, R-Wis., and John Conyers, D-Mich., question the constitutionality of the change and some colleges and small-scale inventors say the change would favor large corporations and stifle academic cooperation.

Alexander Poltorak, head of the American Innovators for Patent Reform, representing independent inventors, university researchers and small companies, said the bill gives big corporations an advantage by weakening the one-year grace period under which an inventor can develop his product before filing for a patent and giving corporations more post-grant challenging rights.

He said the first-to-file system will lead to a rush to file where "large companies with in-house attorneys will always be able to beat small inventors and universities in the race to the patent office."