In this case Teva Pharmaceutical Industries Ltd challenged the validity of Pfizer Pharmaceuticals Inc’s patent for the drug Viagra. Teva stated that Pfizer had not met the disclosure requirements set out in the Canadian Patent Act. The main issue on appeal was whether Pfizer had failed to properly disclose its invention when it obtained the patent for Viagra.

This case addresses the distinction between the requirements to disclose an invention to the public in general terms (enablement) and the separate requirement to disclose the best mode of carrying out the invention. The district court found the patents at issue invalid due to lack of enablement. The United States Court of Appeals affirmed the judgment of the district court, but on different legal grounds, i.e.

The United States Court of Appeals for the Second Circuit held that a prior art to be an anticipation must bear within its four corners adequate directions for the practice of the patent. If the earlier disclosure offers no more than a starting point for further experiments, if its teaching will sometimes succeed and sometimes fail, if it does not inform the art without more how to practice the new invention, it has not correspondingly enriched the store of common knowledge, and it is not an anticipation.

The the Court of Appeals for the Federal Circuit held that for the patenting of microorganisms the best mode disclosure requirement does not necessarily entail an obligation by the patent applicant to deposit a sample of the claimed microorganism.

The Federal Circuit remanded for trial (further clarification of facts) to the district court a number of motions for summary judgment regarding the validity and the infringement of certain product claims and product-by-process claims. The Federal Circuit inter alia decided that in litigation (concerning patent infringement and validity), patent claims must be construed in a similar manner as under patent prosecution (concerning the grant of a patent).

The United States Court of Customs and Patent Appeals (CCPA), which was the predecessor of the United States Court of Appeals for the Federal Circuit reversed a decision by the United States Patent Office (USPTO) to reject a patent application on the basis of alleged improper use of the “Markush claims” format. The CCPA confirmed unity of the claimed invention at issue and therefore considered the Markush claims format as being properly used.

The United States Supreme Court ruled that amending (i.e. narrowing) a patent claim during prosecution does not necessarily result in a complete bar to the doctrine of equivalents. It rejected the Federal Circuit’s decision that a complete bar to equivalents always results when a claim is narrowed during prosecution and thereby confirmed its own case law.