U.S. Patent Act
..Part III. Patents and Protection of Patent Rights
....Chapt. 29. Remedies for Infringement
The owner of an interfering patent may have relief against the owner of another by civil action, and the court may adjudge the question of the validity of any of the interfering patents, in whole or in part. The provisions of the second paragraph of section 146 of this title [35 USCS Sect. 146] shall apply to actions brought under this section.