Can a single unexpected property overcome an obviousness rejection?

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.

A single unexpected property may be sufficient to overcome an obviousness rejection, but its significance is crucial. The MPEP provides an example:

“Evidence that the compound was unexpectedly nonaddictive was sufficient to overcome the obviousness rejection. Although the compound also had the expected result of potent analgesia, there was evidence of record showing that the goal of research in this area was to produce an analgesic compound which was nonaddictive, enhancing the evidentiary value of the showing of nonaddictiveness as an indicia of nonobviousness.” (MPEP 716.02(c))

This example demonstrates that a single unexpected property (nonaddictiveness) can overcome obviousness if it’s shown to be particularly significant in the field. The context and importance of the unexpected property in the relevant field of research are critical factors.