Certificates of plant variety protection shall be presumed valid. The burden of establishing invalidity of a plant variety protection shall rest on the party asserting invalidity.
section 2402 of this titlesection 2422 of this title The following shall be defenses in any action charging infringement and shall be pleaded: (1) noninfringement, absence of liability for infringement, or unenforceability; (2) invalidity of the plant variety protection in suit on any ground specified in as a condition for protectability; (3) invalidity of the plant variety protection in suit for failure to comply with any requirement of ; (4) that the asserted infringement was performed under an existing certificate adverse to that asserted and prior to notice of the infringement; and (5) any other fact or act made a defense by this chapter.