Canadian Patent Law Of Obviousness: R.I.P. Fair Expectation Of Success

The question of whether a "fair expectation of success" is the correct legal standard applicable to an obvious to try analysis was finally laid to rest in the Federal Court of Appeal's recent important decision of Eli Lilly v Mylan (2015 FCA 286). A unanimous panel held that a "fair expectation of success" was not the correct standard. Instead, the higher "more or less self-evident" test articulated by the Supreme Court of Canada in Sanofi-Synthelabo (2008 SCC 61) was reaffirmed as the correct legal standard. The higher standard for obviousness makes it more difficult to invalidate a patent, thereby strengthening protection for patent-holders.

The Eli Lilly case was a NOC case. Lilly sought to prevent Mylan from obtaining marketing authorization for generic CIALIS®. The asserted '948 patent was directed to a pharmaceutical formulation of reduced particle size of the active (tadalifil) with particular excipients for ED treatment.

At first instance, the applications judge found the allegation of obviousness justified. With respect to the obvious to try analysis, the court recognized two different legal standards: (i) the so-called "fair expectation of success" standard; and (ii) the "more or less self-evident" standard articulated by the Supreme Court in Sanofi-Synthelabo.

The applications judge held in 2015 FC 178 the correct legal standard was a "fair expectation of success" and applied it, finding the invention obvious to try:

[150] I am also of the view that the person skilled in the art would have considered it obvious to try the excipients in the '948 Patent to achieve a stable, rapid onset tadalafil tablet. ... Moreover, the test is not whether a skilled person would know for certain that a formulation would work or whether there is a guarantee that particular formulations would work ... This would set the bar too high. The test, rather, is whether the skilled person had good reason to pursue predictable solutions or solutions that provide a "fair expectation of success". ...

The Federal Court came to the same conclusion, however, after ostensibly applying the higher "more or less self-evident" standard from Sanofi-Synthelabo:

[151] In light of the prior art and applying this standard, ... a person skilled in the art would have had a high expectation of success in using the excipients and the surfactant of the '948 Patent in obtaining a tadalafil formulation with the desirable bioavailability, and that it was indeed more or less...