Reverse Doctrine of Equivalents

Jay Sandvos
date: Tuesday, June 19, 2007

Let’s not mince words. Being a defendant in patent litigation can be a desperate situation. If the patent owner wins, your whole business could be shut down, your job lost. Yet you only need to prevail on a single issue to win. It’s not a time for the squeamish to leave any possibility of escape unexplored. You can’t be afraid to win ugly.

Yet there is at least one defense that is rarely considered. Many patent lawyers may not even know about it. Many of the ones who do, loathe it as too laughable, too hideous to consider. But is that really a good reason not to give it a whack? If you’re not sure, take a look at the first paragraph again.

What is this horrible creature upon whom we dare not gaze? Lean over close to the page and I will whisper its name in your ear.

Closer.

It is called the reverse doctrine of equivalents.

Now that all the patent lawyers have run screaming out of the room, let’s talk about this strange beast.

First, you should understand about the regular forward flavor of doctrine of equivalents. Every patent concludes with a set of claims that define the patented invention. Receiving a patent means that no one can make, use or sell what the claims describe unless they get permission from the patent owner. Sadly, the literal language of claim can be avoided sometimes by some trivial difference -- substituting an unclaimed staple for a claimed paper clip. It doesn’t sound fair to make such a tiny change to escape an otherwise valuable patent.

To avoid such unfair results, patent law has long recognized that the claims of a patent may cover somewhat more than just the exact literal language of the claims. If an accused product differs from the literal claim language only in a small insignificant way, then it may still infringe under what is known as the doctrine of equivalents. That is, you look at the accused element that is not quite within the literal claim language to see if it functions in the same way as what was claimed and produces the same result. If so, there is not literal infringement, but infringement by equivalents. That sounds fair enough, doesn’t it?

Although the doctrine of equivalents has a long honorable history in the case law of patents, the last time it was discussed and considered at length by the U.S. Supreme Court was in 1950 in a case referred to as Graver Tank. The court analyzed, set forth, and explained the function-way-result test, basing their reasoning on the fundamental fairness of it all. And in passing, the court also explained that such reasoning and fairness also worked in the other direction (cue the dramatic music).

Let’s say you describe and patent a method of analyzing dress patterns to determine how much cloth to cut. What if the literal language of the patent claims seemed to also cover analyzing audio patterns to recognize an unknown speech input? Under Graver Tank, the doctrine of equivalents would work in reverse, you would look at the claim elements and probably conclude that they did not function in the same way to accomplish the same results as the dress patterns that were described by the patent. So even though the claims might be literally infringed, there would not be actual infringement under the reverse doctrine of equivalents.

That also sounds fair enough, doesn’t it? And because it was set forth by the Supreme Court, there are only two ways to get rid of the reverse doctrine of equivalents, by act of Congress or by the Supreme Court reversing itself. Neither of those has occurred. Lower courts are powerless to ignore it. The reverse doctrine of equivalents is still good law.

Yet, since Graver Tank, there is curiously little case law in which subsequent lower courts have grappled with this notion. When the subject occasionally comes up, the court or a commentator spends some time disparaging the reverse doctrine of equivalents, and then points out that the Federal Circuit Court of Appeals (one step below the Supremes and the usual final stop in a patent case) has never upheld or relied upon the reverse doctrine of equivalents to support a finding of noninfringement. But it is also further true that they have never reversed a finding of non-infringement based on reverse doctrine of equivalents. (I don’t think they can, it’s a question of fact that appeals courts cannot directly alter). So, disrespected and abused, the reverse doctrine of equivalents lives on, like a hibernating grizzly bear awaiting the coming of its spring.