Is a chemical compound claim indefinite if a complete structure is not presented?

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.

No, a chemical compound claim is not automatically considered indefinite if a complete structure is not presented. The MPEP 2173.05(t) clarifies this point:

“A claim to a chemical compound is not indefinite merely because a structure is not presented or because a partial structure is presented.”

This guidance is based on court decisions, such as In re Fisher, where the court held that the absence of a complete structure broadens the claim but does not render it indefinite. However, it’s important to note that such claims may raise questions about the sufficiency of disclosure.