Prohibited Words in a Patent – “Must”

I have a list of words that are just plain prohibited in a patent application. I know that other people may use these Prohibited Words, but I have tried to rid them from my lexicon. Some of this may reek of slimy lawyer lingo, but it all has legitimate and practical reasons. This is a first post of several talking about the Prohibited Words.

The first group of Prohibited Words includes those that make definitive and absolute requirement of something in the written description. These are words and phrases like “must,” “have to,” “should,” “ought to,” “necessary,” “requires,” or any other similar words or phrases. In every situation, the proper term is “may,” “could,” “potentially,” or a similar phrase. I also try to avoid words like “never” and “always” as well.

When describing how something works, it is very easy to say that something (a machine, process, circuit, compound, etc.) must include certain elements. The problem with such statements is that they inherently limit the invention to those elements.

A recent litigated case involving a Colorado inventor hinged on the fact that the patent drafter stated “the benefit is…” rather than “a benefit is…” or “a potential benefit is …”. The entire case hinged on the fact that the court read the phrase to mean that the claimed invention must have the limitation. Literally millions of dollars were on the line because of an inadvertent error during patent drafting.

Many times, we think we don’t care if the invention is limited to specific elements because we cannot even imagine a version of the invention without those elements. But that is very myopic.

Most inventors are myopic at some level, which is completely natural. They see the world and their invention from a certain vantage point. Some inventors are better than others at seeing the limitations of their invention or envisioning how other people may transform or build on their invention. The problem is that inventors are horrible at foretelling how technologies and the market will change with respect to their invention.

Remember that an issued patent may be in force for 20 years after drafting. Who knows what kind of new technology or new product on the market will make certain portions of the invention more or less important. Can you say with absolute certainty that there are absolutely no possible embodiments of your invention that does not have absolute positively have to have a specific element? The answer is always no. Thus, we allow for the possibility that our novel mousetrap may or may not have a latch mechanism in the description, even if we have the limitation in the claims.