Constructive Reduction to Practice
2002, Gallagher & Dawsey Co., LPA
October 2002

This is the third part of a three part series dealing with three important stages in the development of an invention; conception, actual, and constructive, reduction to practice. The first two articles, dealing with conception and actual reduction to practice, may be viewed on our web site:

Constructive reduction to practice is perhaps the simplest to understand of the possible points where an invention is created. An invention is constructively reduced to practice when a formal application disclosing the invention is filed with the Patent and Trademark Office. An invention does not have to be built ("actually reduced to practice") to suffice; it is enough if the enabling disclosure allows one skilled in the art to build the claimed invention. Therefore, since the date of an application is the date of constructive reduction to practice, a patent application cannot have a reduction to practice date that is later than its filing date. However, with the doctrines of conception plus diligence and actual reduction to practice, many inventors are able to establish priority dates far earlier than the application's filing date. Remember, of course, that an application's filing date is the date it is received in the patent office, unless it is filed using the U.S. Post Office's Express Mail service. Recent disruptions in mail service have made Express Mail even more critical for filing applications.
While the concept of constructive reduction to practice is straightforward in most situations, a number of special situations warrant your attention. First, a Provisional Patent Application (PPA) is a constructive reduction to practice only if it contains adequate disclosure that would support a nonprovisional utility application. Since provisional applications are not examined, it is incumbent on the inventor to make sure that the disclosure of a PPA is fully enabling under 35 U.S.C. 112. A receipt for a PPA is not a guarantee of constructive reduction to practice

Secondly, an abandoned patent application, if there was no subsequent copending application, is not a sufficient basis for a constructive reduction to practice, and is, in fact, inadequate for any purpose other than to serve as evidence of conception.
As an alternative to abandoning a patent application, if an inventor wants to abandon an application and prevent anyone else from ever getting a patent on the invention, an inventor can file a Statutory Invention Registration (SIR). A SIR, unlike an abandonment action, is considered a constructive reduction to practice. However, the defensive use of SIR's is a sophisticated technique that should not be undertaken without careful consultation by an experienced patent attorney.