Review Of US Patent Claims Construction Gets Canadianized

On January 20, 2015, the US Supreme Court rendered its precedent-setting decision in Teva¹ that reversed the Federal Circuit's practice of reviewing all District Court claim constructions de novo on appeal. Instead the Supreme Court found that some decisions are entitled to deference as a consequence of certain factual findings that require Courts of Appeal to apply a "clear error" standard of review, and consequently, bringing the review of US claims constructions methodology more in line with the Canadian approach.

The phrase within the claim at issue in Teva was "molecular weight of 5 to 8 kilodaltons", which Sandoz argued was "fatally indefinite" as the claim did not establish which method of calculation should be used. After considering the expert evidence, the District Court concluded the claim was sufficiently definite as the skilled person would understand "molecular weight" to be calculated by "peak average molecular weight". The Federal Circuit disagreed,