What are the requirements for a proper consonance in divisional applications?

This page is an FAQ based on guidance from the Manual of Patent Examining Procedure. It is provided as guidance, with links to the ground truth sources. This is information only: it is not legal advice.

Proper consonance in divisional applications is crucial for maintaining the protection against double patenting rejections under 35 U.S.C. 121. According to MPEP 804.01:

“Consonance requires that the line of demarcation between the ‘independent and distinct inventions’ that prompted a restriction requirement be maintained … in the divisional application.”

To maintain proper consonance:

• The claims of the divisional application must be directed to the elected invention in the parent application.
• The claims must not overlap with the non-elected invention(s) in the parent application.
• The restriction requirement in the parent application must be maintained throughout prosecution.

Failure to maintain consonance may result in the loss of the safe harbor protection against double patenting rejections provided by 35 U.S.C. 121.