Can a partial assignee file a patent application as the sole applicant?

No, a partial assignee cannot file a patent application as the sole applicant. The MPEP clarifies this point:

Because all parties having any portion of ownership in a patent property must act together as a composite entity in patent matters before the Office, a partial assignee (e.g., a party who owns 50% of the interest) cannot on its own file a patent application as the applicant.

This means that if multiple parties have ownership interests in the invention, they must act together to file the patent application. For more information on joint ownership, see MPEP § 301.

To learn more:

• partial assignee
• sole applicant
• joint ownership
• patent application