Minnesota Statutes Declaratory, Corrective and Administrative Remedies (Ch. 553-569) § 556.11. Letters patent, vacation

(1) that such letters were obtained by means of some fraudulent suggestion or concealment of a material fact, made by or with the consent or knowledge of the person to whom they were issued;

(2) that such letters were issued through mistake, or in ignorance of a material fact; or

(3) that 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 were granted, or have by any other means forfeited the interest acquired thereunder.