Is absolute predictability required for a reasonable expectation of success?

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, absolute predictability is not required for a reasonable expectation of success in patent law. The MPEP 2143.02 states:

“Obviousness does not require absolute predictability, but at least some degree of predictability is required.”

This means that while complete certainty is not necessary, there should be a reasonable level of predictability that the proposed combination or modification of prior art would work. The courts have consistently held that the expectation of success need only be reasonable, not absolute.

For example, in Pfizer, Inc. v. Apotex, Inc., the Federal Circuit reasoned that “the expectation of success need only be reasonable, not absolute.”