U.S. patents to be more narrowly interpreted

Many years ago, significant differences between patents and products accused of infringing patents often went unnoticed by juries because they couldn't understand the technologies. As a consequence, avoiding a charge of infringement was difficult. On the other hand, significant enhancements in technologies sometimes were mistakenly found by judges to have been "obvious," leading to determinations of patent invalidity.

If the opinion was based on the "doctrine of equivalents," a different opinion might well be given now

Today, the environment for patents is much different. It's usually very hard to prove that a patent is invalid. The courts give great weight to the decision made by the U.S. Patent & Trademark Office to issue a patent. Now defendants bear the burden of proving invalidity and can only carry this burden by evidence that is "clear and convincing." This is higher than the "preponderance of evidence" standard used in most civil litigation.

At the same time, however, the courts are becoming far less willing to allow patents to be interpreted broadly and have shifted the responsibility for interpreting patents from juries to judges, who often favor a narrower interpretation.

One of the most controversial infringement principals has been the "doctrine of equivalents." The scope of an invention is defined in a patent by a list of components called a "claim." (A claim also can recite a list of steps in a process. And there can be several claims.) To infringe, the accused product must contain each component listed in one patent claim. This is known as the "all elements rule."

The "doctrine of equivalents" is an exception to the all elements rule. Under this doctrine, an accused product will infringe a patent claim, even if it lacks a component listed in that claim, if it contains a corresponding component that is only "insubstantially different." The U.S. Supreme Court created and maintained this doctrine to prevent an insignificant difference from circumventing a patent.

However, the United States Court of Appeals for the Federal Circuit-the subordinate court that determines all patent appeals-has disliked the doctrine of equivalents because its reach is often hard to predict. In what arguably is an end-run around the Supreme Court, the Federal Circuit surprised many at the end of last year by severely restricting the availability of this doctrine. In Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., the Federal Circuit said that this doctrine could not be used to expand the reach of a component that had been added by an amendment-i.e. a component that was not listed in the patent claim at filing but rather was added later during the pursuit of the patent.

Festo is likely to alter the result in several patent infringement cases now underway. Many components in a patent claim are not placed in that claim until after the patent application is filed. Under Festo, an added component will no longer be entitled to any range of equivalents-a mere "insubstantial difference" will avoid infringement.

Companies that have received a legal opinion on the question of infringement should have that opinion re-evaluated. If the opinion was based on the "doctrine of equivalents," a different opinion might well be given now.

Much greater attention also should be given to the patent claims that are filed with the original application. Although components can still usually be added later by amendment, there is going to be a big cost-an infringer may be able to avoid the patent by making an insubstantial change to an added component.

Marc. E. Brown is an EE, partner in the Los Angeles office of Oppenheimer Wolff & Donnelly LLP and Co-Chair of its Internet & E-commerce Group. He can be reached at mbrown@oppenheimer.com.