Oregon Revised Statutes Remedies and Special Actions and Proceedings § 30.600

(1) When the letters patent were issued by means of some fraudulent suggestion or concealment of a material fact by the person to whom the letters were issued, or with the knowledge and consent of the person;

(2) When the letters patent were issued through mistake or in ignorance of a material fact; or

(3) When the patentee, or those claiming under the patentee, have done or omitted an act, in violation of the terms and conditions on which the letters patent were issued, or have by any other means forfeited the interest acquired under the letters.