PUBLIC LAWS-CH. 540-JULY 5, 1946 Oonditiona 21 Stat. 502; 33 Stat. 724. 15U.S. . § § 81-109. Post,p. 444 . Determination of registration rights. Refusal of registra- tion, etc. (ondlitions and lim- itations. Ante, p. 428. Laches, estoppel, etc. registered mark in commerce for the goods or services on or in con- nection with which such registered mark has been in continuous use for five consecutive years subsequent to the date of such registration and is still in use in commerce, shall be incontestable: Provided,That- (1) there has been no final decision adverse to registrant's claim of ownership of such mark for such goods or services, or to registrant's right to register the same or to keep the same on the register; and (2) there is no proceeding involving said rights pending in the Patent Office or in a court and not finally disposed of; and (3) an affidavit is filed with the Commissioner within one year after the expiration of any such five-year period setting forth those goods or services stated in the registration on or in connection with which such mark has been in continuous use for such five consecutive years and is still in use in commerce, and the other matters specified in subsections (1) and (2) hereof; and (4) no incontestable right shall be acquired in a mark or trade name which is the common descriptive name of any article or substance, patented or otherwise. Subject to the conditions above specified in this section, the incontestable right with reference to a mark registered under this Act shall apply to a mark registered under the Act of March 3, 1881, or the Act of February 20, 1905, upon the filing of the required affidavit with the Commissioner within one year after the expiration of any period of five consecutive years after the date of publication of a mark under the provisions of subsection (c) of section 12 of this Act. The Commissioner shall notify any registrant who files the above-prescribed affidavit of the filing thereof. INTERFERENCE SEC. 16. Whenever application is made for the registration of a mark which so resembles a mark previously registered by another, or for the registration of which another has previously made appli- cation, as to be likely when applied to the goods or when used in connection with the services of the applicant to cause confusion or mistake or to deceive purchasers, the Commissioner may declare that an interference exists. No interference shall be declared between an application and the registration of a mark the right to the use of which has become incontestable. SEC. 17. In every case of interference, opposition to registration, application to register as a lawful concurrent user, or application to cancel the registration of a mark, the Commissioner shall give notice to all parties and shall direct the examiner in charge of interferences to determine and decide the respective rights of registration. SEC. 18. In such proceedings the Commissioner may refuse to reg- ister the opposed mark, may cancel or restrict the registration of a registered mark, or may refuse to register any or all of several inter- fering marks, or may register the mark or marks for the person or persons entitled thereto, as the rights of the parties hereunder may be established in the proceedings: Provided,That in the case of the regis- tration of any mark based on concurrent use, the Commissioner shall determine and fix the conditions and limitations provided for in sub- section (d) of section 2 of this Act. SEC. 19. In all inter partes proceedings equitable principles of laches, estoppel and acquiescence, where applicable may be consid- ered and applied. The provisions of this section shall also govern proceedings heretofore begun in the Patent Office and not finally determined. 434 [60 STAT.