definiens: means any direct or indirect dispute or challenge, or any knowing, willful, or reckless assistance in the dispute or challenge, of the va lidity, patentability, priority, inventorship, ownership or enforceability of any Editas Background Patent or any claim thereof, or opposition or assistance in the opposition of the grant of any letters patent within the Editas Background Patents, in any l egal or administrative proceedings, including in a court of law, before the United States Patent and Trademark Office or other agency or tribunal in any jurisdiction, or in arbitration including, without limitation, by reexamination, inter partes review, o pposition, interference, post -grant review, nullity proceeding, preissuance submission, third party submission, derivation proceeding or declaratory judgment action ; provided, however, that the term Patent Challenge shall not include ( i ) [COMPANY] or its Af filiates being an essential party in any patent interference proceeding before the United States Patent and Trademark Office, which interference [COMPANY] or its Affiliates acts in good faith to try to settle, ( ii ) [COMPANY] or its Affiliates, due to its sta tus as an exclusive licensee of Patents other than the Editas Background Patents, being named by the licensor of such Patents as a real party in interest in such an interference, so long as [COMPANY] or the applicable Affiliate either abstains from particip ation in, or acts in good faith to settle, the interference, ( iii ) any assertion by [COMPANY] or its Affiliates relating to validity, patentability, scope, priority, construction, non -infringement, inventorship, ownership or enforceability as a defense in a ny legal proceeding, administrative proceeding or arbitration brought by Editas, its Licensee or assignee asserting infringement against [COMPANY] or its Affiliates or ( iv ) any dispute or challenge brought by a Third Party which subsequently becomes an Affi liate of [COMPANY], provided [COMPANY] causes such Third Party to take commercially reasonable steps to rescind such dispute or challenge within [ * * ] days after such Third Party becomes an Affiliate of [COMPANY]