501.03   Effect of Failure to Record Assignment  

15 U.S.C. §1060(a)(3) 

(Extract)

  • (3) * **Acknowledgment shall be prima facie evidence of the execution of an assignment, and when the prescribed information reporting the assignment is recorded in the United States Patent and Trademark Office, the record shall be prima facie evidence of execution.
  • (4) An assignment shall be void against any subsequent purchaser for valuable consideration without notice, unless the prescribed information reporting the assignment is recorded in the United States Patent and Trademark Office within 3 months after the date of the assignment or prior to the subsequent purchase.

See TMEP §§503 et seq. regarding the recordation of assignments in the Assignment Recordation Branch of the USPTO.