Patent Interference - What Is It?

A Patent Interference is a rare thing. About one percent of the applications filed become involved in an interference proceeding. As a point if reference - in my 13 years in this business I have never encountered a patent interference. So everything I am saying here is not based on experience, but on study - just in case.

What happens here is that occasionally (rarely) two or more applications are filed by different inventors claiming substantially the same patentable invention. The patent can only be granted to one of them, and a proceeding known as an “interference” is instituted by the Office to determine who is the first inventor and entitled to the patent. Interference proceedings may also be instituted between an application and a patent already issued, provided that the patent has not been issued, nor the application been published, for more than one year prior to the filing of the conflicting application, and provided also that the conflicting application is not barred from being patentable for some other reason.

Once a patent interference is declared each party to the proceeding must submit evidence of facts proving when the invention was made. In view of the necessity of proving the various facts and circumstances concerning the making of the invention during an interference, inventors must be able to produce evidence to do this. If no evidence is submitted a party is restricted to the date of filing the application as his/her earliest date. The priority question is determined by a board of three administrative patent judges on the evidence submitted. From the decision of the Board of Patent Appeals and Interferences, the losing party may appeal to the Court of Appeals for the Federal Circuit or file a civil action against the winning party in the appropriate United States district court.

New Terminology

During a patent interference there are two terms that will come up that are important. One is "conception of the invention", and the other is "reduction to practice". They both sound simple but in case law turn out to be quite contentious.

One definition of conception of the invention from case law is "the "formation in the mind of the inventor, of a definite and permanent idea of the complete and operative invention, as it is hereafter to be applied in practice." Sounds good, but as you can imagine both sides in the interference will have different views of who had that "permanent idea" in their mind first. As mentioned above - evidence must be provided. This is why , as I have mentioned elsewhere on this website keeping a good dated, signed, and witnessed notebook can be very important. If you do not have that kind of evidence your filing date will probably be viewed as your conception of the invention.

Reduction to practice refers to the actual construction of the invention in physical form. In the case of a machine it includes the actual building of the machine, in the case of an article or composition it includes the actual making of the article or composition, in the case of a process it includes the actual carrying out of the steps of the process. Actual operation, demonstration, or testing for the intended use is also usually necessary. However, the filing of a regular application for patent completely disclosing the invention is treated as equivalent to reduction to practice.

The inventor who proves to be the first to conceive the invention AND the first to reduce it to practice will be held to be the prior inventor.

In practice the situation can get quite complicated. Record you ideas in a proper inventors notebook!


Patent Interferences
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Mike Ervin
Mike Ervin - Cost Effective Small Business Patent Protection.

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