While I wasn’t necessarily looking for them, some may have noticed prominent advertisements last fall announcing that the price of Viagra had dropped considerably. The price reduction was a direct result of the Supreme Court of Canada’s headline-making decision to invalidate Pfizer’s patent that protected the drug. After the patent was invalidated, generic drugs went on the market and Pfizer made a strategic decision to lower its price. Legal decisions concerning patents don’t often make the front pages of newspapers. Therefore, a brief review is warranted.

The legal issue at the heart of the Viagra case is known as the patent bargain, which forms the basis for the entire patent system. Essentially, in return for disclosing to the public an invention that is new, inventive and useful, the inventor receives from the state a time-limited monopoly to exploit the invention (20 years to be exact). Some people feel that the idea of a state-granted monopoly runs contrary to the principles of a capitalistic society. However, the reasoning behind the patent bargain is that it is advantageous for a society to reap the benefits of innovation, which otherwise may remain secret, in exchange for the inefficiencies of a limited monopoly. The hard coinage that must be exchanged to obtain a patent is a full and complete disclosure of the invention, such that the invention can be easily worked by those skilled in the art after expiration of the patent. Without complete disclosure, the inventor breaks the patent bargain and any issued patent may be deemed invalid.

A patent generally has two main parts: a description setting out how the invention works and the claims, which specifically define the inventor’s monopoly. The patent protecting Viagra is a typical pharmaceutical patent that discloses a broad generic formula covering quintillions of compounds. It is subsequently narrowed to focus upon certain preferred compounds, which Pfizer had likely tested for their in vitro biological activity. One of these preferred compounds was sildenafil, later branded as Viagra. However, rather than specifically identifying sildenafil in the activity data, Pfizer stated that “one of the especially preferred compounds of the invention has an IC50 = 6.8 nm.” At trial, Pfizer argued that it had provided a full and complete disclosure of the invention because sildenafil was described as one of two especially preferred compounds that were specifically claimed at the end of the patent. A skilled person would therefore be able to easily identify which compound was of particular interest. Unfortunately for Pfizer, the Supreme Court disagreed and ruled that Pfizer was required to disclose which compound was sildenafil in the description of the patent. As Pfizer failed to state in clear terms what the invention was, the Court found that the company were not living up to its end of the bargain. The issue likely could have been avoided had Pfizer simply stated in the patent that Viagra was the compound that had been tested.

Occasionally I am asked by inventors whether they could withhold certain information from a patent application — the secret something that makes the invention work really well. My answer is always the same: it’s best practice to disclose everything you know about your invention. In view of the Supreme Court’s decision, the stakes for withholding information from a patent are significant, including the risk of having the patent deemed invalid. And lest you think that no one would ever discover that important information was withheld from a patent, parties to patent litigation often spend millions of dollars to ensure no stone is left unturned. To paraphrase an old adage, in the patent system, disclosure is the best policy.

Mike Fenwick is a patent lawyer with Bereskin and Parr LLP in Toronto and holds a master’s degree in organic chemistry.