Beyond A 'Reasonably Diligent Search' In An Obviousness Attack

In Aux Sable Liquid Products LP et al. v. JL Energy Transportation Inc., 2019 FC 581 [Aux Sable], the Federal Court eliminated the "reasonably diligent search" test as the applicable test for establishing the scope of citable prior art in an obviousness attack. This decision impacts what constitutes "the state of the art" for an obviousness attack in a Canadian patent impeachment proceeding and may increase the vulnerability of patents to impeachment proceedings. However, we caution that this may not be the last word on the subject, as recently the Federal Court of Appeal in Tearlab Corporation v. I-MED Pharma Inc., 2019 FCA 179, appeared to accept that the reasonably diligent search test was applicable.

The "Reasonably Diligent Search" Test

The impeachment proceedings against the defendant's patent raised the issue of whether the enactment of section 28.3, the obviousness provision of the Canadian Patent Act, displaced the common law "reasonably diligent search" test. Prior to the enactment of this provision, and until the decision in Aux Sable, a party alleging obviousness had to establish that a prior art reference had not only been publicly disclosed but was locatable by a person of ordinary skill in the art through a reasonably diligent search, in order for the reference to form part of the state of the art. References the court did not consider locatable through a reasonably diligent search did not form part of the state of the art in an obviousness attack, though such references were citable in an anticipation attack.

The Aux Sable Decision

In Aux Sable, the plaintiffs successfully argued that section 28.3 eliminated the "reasonably diligent search" test and that previous jurisprudence had not caught up to the statutory change. This decision thus establishes that all references disclosed to the public prior to the applicable date prescribed by section 28.3, not only those locatable through a reasonably diligent search, form the state of the art...