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 in an obviousness attack. This effectively removes the distinction between the totality of available prior art and the state of the art in an obviousness attack.
This decision likely lowers the burden on a party alleging obviousness as the limitations imposed by the "reasonably diligent search" test no longer apply. All publicly disclosed prior art located by the challeging party will now form part of the state of the art in an obviousness attack. It may additionally result in a more streamlined obviousness analysis in patent impeachment proceedings because courts will not need to determine which references were reasonably locatable.
For patentees, the elimination of the "reasonably diligent search" test may make patents more vulnerable to obviousness allegations and impeachment proceedings. Patents in scientific or technical fields where information is presented and published regularly may be especially vulnerable. The elimination of the test means that even a presentation at a small conference or an article published in an obscure journal, for instance, would qualify as part of the state of the art for the purposes of an obviousness attack. In view of the broadened scope of citable prior art in an obviousness attack established by Aux Sable, patentees and legal practitioners will therefore likely need to search beyond diligently for prior art and be increasingly wary of obviousness allegations.
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