How does the USPTO handle post-filing date evidence in enablement determinations?

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.

The USPTO generally discourages the use of post-filing date evidence in enablement determinations. According to MPEP 2164.05(a):

“In general, the examiner should not use post-filing date references to demonstrate that a patent is not enabled.” However, there are exceptions:

• A later-dated reference may provide evidence of what one skilled in the art would have known on or before the effective filing date.
• If a publication demonstrates that those of ordinary skill in the art would find a particular invention was not enabled years after the filing date, it could be evidence that the claimed invention was not possible at the time of filing.

The MPEP also notes: “While a later dated publication cannot supplement an insufficient disclosure in a prior dated application to make it enabling, an applicant can offer the testimony of an expert based on the publication as evidence of the level of skill in the art at the time the application was filed.”