Avoiding The Hindsight Trap In The Context Of A Patent Obviousness Analysis

While courts have often warned that hindsight bias should be avoided when assessing whether a patented invention would have been obvious to the skilled person, the application of this principle can be challenging in practice.

Section 28.3 of the Patent Act provides that the subject matter of a claim in a patent application must not have been obvious to a person skilled in the art as of the claim date. When the validity of a patent is challenged on the basis of obviousness'which is the case in almost all patent cases where validity is at issue'Canadian courts apply the well-known four-part obviousness test established by the Supreme Court of Canada in Apotex Inc v Sanofi-Synthelabo Canada Inc¹ Steps one to three involve identifying the state of the art, determining the inventive concept of the claim, and identifying the differences between the inventive concept and the state of the art. Step four is to assess whether the differences would have been obvious to the skilled person without knowledge of the claimed invention.

The Federal Court of Appeal, in Janssen-Ortho Inc v Novopharm Ltd,² proposed a list of factors that can be considered at step four. The principal factors are:

• What body of knowledge and information would the ordinary person skilled in the art be expected to have, or to be reasonably able to obtain, as of the date of the alleged invention?
• What was the climate in the relevant field at the time the alleged invention was made?
• What motivation existed at the time the alleged invention was made to solve a recognized problem?
• What effort and time were involved? Were those efforts routine or were there many decisions involved?

In Janssen-Ortho, the court also identified so-called secondary factors that may be considered, such as the invention's commercial success and any awards it has earned.

Almost every Canadian court decision that has analyzed the validity of a patent on the grounds of obviousness initially acknowledges the impropriety of hindsight analysis. Justice Hugessen's eloquent warning is often cited:

Every invention is obvious after it has been made, and to no one more so than an expert in the field. Where the expert has been hired for the purpose of testifying, his infallible hindsight is even more suspect. It is so easy, once the teaching of a patent is known, to say, "I could have done that"; before the assertion can be given any weight, one must have a satisfactory answer to the question, "Why didn't you?"³

However, avoiding the...