Defendants’ burden of proof for invalidity is not raised because a reference was previously before the PTO; statements made during prosecution to rebut enablement rejections under Section 112 may be used as proof of motivation to combine references under Section 103.

When a generic drug manufacturer launched its approved product at risk, the district court entered a preliminary injunction to stop sales. The generic drug manufacturer appealed on the grounds that the district court applied the wrong legal standard in finding it had not raised a substantial question of invalidity regarding obviousness of the asserted claims. The Federal Circuit agreed with the generic drug manufacturer; the court vacated the preliminary injunction and remanded for further proceedings.

The presumption of validity does not change depending on whether a given argument or prior art reference was before the PTO during prosecution of the asserted patent. “The burden does not suddenly change to something higher—‘extremely clear and convincing’ or ‘crystal clear and convincing evidence’—simply because the prior art references were considered by the PTO.” Instead, the presence of the reference or argument before the PTO is a factor the fact finder may take into account when determining how much weight to give to the evidence. The district court erred by requiring an enhanced burden of proof by the generic drug manufacturer to establish obviousness because the art was previously before the PTO.

The Federal Circuit also found motivation to combine prior art references within the references cited and prior art products. The court rejected the district court’s refusal to use statements made during prosecution to overcome an enablement rejection as proof that modifying the prior art would be “routine experimentation” by a person of skill in the art. “[T]he applicant’s characterization of the predictability and skill in the art during prosecution provides further evidence that it would have been a routine and obvious design choice.”

A copy of the opinion can be found here.