Who can sign papers in a patent application when there’s no attorney of record?

When there’s no attorney of record, the signatories for patent application papers depend on the filing date and the applicant type. For applications filed before September 16, 2012, MPEP § 407 states: “All papers filed in the application must be signed: (1) by all named applicants unless one named applicant has been given a power of attorney to sign on behalf of the remaining applicants, and the power of attorney is of record in the application; or (2) if there is an assignee of record of an undivided part interest, by all named applicants retaining an interest and such assignee; or (3) if there is an assignee of the entire interest, by such assignee; or (4) by a registered patent attorney or agent not of record who acts in a representative capacity under the provisions of 37 CFR 1.34.”

For applications filed on or after September 16, 2012: “All papers must be signed by: (1) a patent practitioner of record; (2) a patent practitioner not of record who acts in a representative capacity under the provisions of 37 CFR 1.34; or (3) the applicant, except that papers submitted on behalf of a juristic entity applicant must be signed by a patent practitioner.”