'Secondary' Evidence of Obviousness is Not Secondary

Abstract

In assessing whether a claimed invention is obvious, a court will hear evidence from expert witnesses as to the knowledge and state of mind of a hypothetical skilled person at the relevant time, then “assume the mantle” of that person and assess whether the invention would have been obvious to him or her. The court may also consider the circumstances of the invention and its reception, most prominently whether there was a long-felt need and commercial success. This type of evidence is now commonly know as “secondary” evidence. The UK Court of Appeal has said that secondary evidence is substantively secondary to the evidence of expert witnesses, while in contrast in US law failure to consider secondary evidence is an error of law. This note argues that the view that so-called secondary evidence is inherently of lesser importance than the evidence of expert witness is wrong as a matter of policy.