Title 35, PatentsRelease 119-102
§121 Divisional Applications
Title 35 › PART II — PATENTABILITY OF INVENTIONS AND GRANT OF PATENTS › CHAPTER 11 — APPLICATION FOR PATENT › § 121
Summary
The Director can require an application that claims two or more inventions to be limited to one. A divisional filed under section 120 keeps the original filing date. If the divisional is filed before the other patent issues, that other patent cannot be used as a reference. A patent’s validity cannot be questioned because the Director failed to require restriction.
Full Legal Text
Title 35, §121
Patents, Source: USLM XML via OLRC
If two or more independent and distinct inventions are claimed in one application, the Director may require the application to be restricted to one of the inventions. If the other invention is made the subject of a divisional application which complies with the requirements of section 120 it shall be entitled to the benefit of the filing date of the original application. A patent issuing on an application with respect to which a requirement for restriction under this section has been made, or on an application filed as a result of such a requirement, shall not be used as a reference either in the Patent and Trademark Office or in the courts against a divisional application or against the original application or any patent issued on either of them, if the divisional application is filed before the issuance of the patent on the other application. The validity of a patent shall not be questioned for failure of the Director to require the application to be restricted to one invention.
Legislative History
Notes & Related Subsidiaries
Historical and Revision Notes
This section enacts as law existing practice with respect to division, at the same time introducing a number of changes. Division is made discretionary with the Commissioner. The requirements of section 120 are made applicable and neither of the resulting patents can be held invalid over the other merely because of their being divided in several patents. In some cases a divisional application may be filed by the assignee.
Editorial Notes
Amendments
2011—Pub. L. 112–29, § 20(j), struck out “of this title” after “120”. Pub. L. 112–29, § 4(a)(2), struck out “If a divisional application is directed solely to subject matter described and claimed in the original application as filed, the Director may dispense with signing and execution by the inventor.” before “The validity of a patent”. 2002—Pub. L. 107–273 made technical correction to directory language of Pub. L. 106–113. See 1999 Amendment note below. 1999—Pub. L. 106–113, as amended by Pub. L. 107–273, substituted “Director” for “Commissioner” wherever appearing. 1975—Pub. L. 93–596 substituted “Patent and Trademark Office” for “Patent Office”.
Statutory Notes and Related Subsidiaries
Effective Date
of 2011 AmendmentAmendment by section 4(a)(2) of Pub. L. 112–29 effective upon the expiration of the 1-year period beginning on Sept. 16, 2011, and applicable to any patent application that is filed on or after that
Effective Date
, see section 4(e) of Pub. L. 112–29, set out as a note under section 111 of this title. Amendment by section 20(j) of Pub. L. 112–29 effective upon the expiration of the 1-year period beginning on Sept. 16, 2011, and applicable to proceedings commenced on or after that
Effective Date
, see section 20(l) of Pub. L. 112–29, set out as a note under section 2 of this title.
Effective Date
of 1999 AmendmentAmendment by Pub. L. 106–113 effective 4 months after Nov. 29, 1999, see section 1000(a)(9) [title IV, § 4731] of Pub. L. 106–113, set out as a note under section 1 of this title.
Effective Date
of 1975 AmendmentAmendment by Pub. L. 93–596 effective Jan. 2, 1975, see section 4 of Pub. L. 93–596, set out as a note under section 1111 of Title 15, Commerce and Trade.
Reference
Citations & Metadata
Citation
35 U.S.C. § 121
Title 35, Patents
Last Updated
Aug 21, 2026
Release point: 119-102