Post KSR, KSR International Co. v. Teleflex Inc., (see IP Update, Vol. 10, No. 5), the “obvious to try” test has become a hot topic for U.S. patent lawyers. That same test has been recently reviewed by the House of Lords in the United Kingdom (Conor v. Angiotech [2008], UKHL 49), and the principles laid down by the House of Lords have now been applied by the UK High Court in the case of Generics UK Ltd. v. Daiichi ([2008], EWHC 2413), an application that has now been upheld by the Court of Appeal ([2009], EWCA Civ 646).

Pre-KSR, the U.S. and UK appeared to have completely opposite approaches as to how the obvious to try test should be applied when assessing validity. While the pre-KSR Federal Circuit did not embrace this test, the approach of the UK courts favored a more liberal variant of the obvious to try test, i.e., the “worth a try” test.

In Saint-Gobain v. Fusion Provida, the UK position retracted slightly from the “worth a try approach” and held that the mere possible inclusion of something within a research program, on the basis that one would find out more, was not enough to show obviousness.

The House of Lords considered the application of this test and approved the principles set out by Kitchin J in Generics v. Lundbeck (using language similar to the KSR decision): “The question of obviousness must be considered on the facts of each case. The court must consider the weight to be attached to any particular factor in the light of all the relevant circumstances. These may include such matters as the motive to find a solution to the problem the patent addresses, the number and extent of the possible avenues of research, the effort involved in pursuing them and the expectation of success.”

This test has now been applied at the first instance court in Generics v. Daiichi and affirmed by the Court of Appeal. The Daiichi case involved one of a several recent enantiomer patent actions in the UK, where the racemate (ofloxacin) forms part of the prior art. (A racemate is a combination of two or more enantiomers). The patent in suit claimed one of the enantiomers which made up the racemate. It was shown that this particular enantiomer had greater activity on its own than when combined with others in the racemate. The obviousness arguments centered around methods of separation of the racemate into individual enantiomers and which routes the skilled person would try. In the first instance judgment, the court held that the enantiomers of the invention could not be separated relatively easily; on the contrary, their resolution into separate enantiomers involved a research program with a highly uncertain outcome. On that basis, the court held that the person skilled in the art would have instead turned his attention to the development of new molecules. Validity was therefore upheld. Application of the test confirms the UK courts’ retreat from the previous “worth a try” approach in favor of the slightly more stringent obvious to try test.