Identical Inventions Developed By Two Separate Inventors

An “interference” is a proceeding instituted in the Patent and Trademark Office when two or more inventors are claiming the same patentable invention. An interference may be declared between two or more pending applications, or between one or more pending applications and one or more unexpired patents. In the United States, the first party to invent, not the first party to file an application, is entitled to receive the patent for the invention. Thus, although there is a presumption that inventions are made in the order of their respective filing dates, it is possible for a person with a later filing date to show that he or she was the first party to invent.

In an interference proceeding each party must submit evidence to the Patent Office to prove his or her actual date of invention. The Patent Office will then determine which party was the first to invent. In making this determination, the Patent Office will consider the following factors: the date on which each inventor mentally conceived the invention, whether the inventors were diligent in reducing their inventions to practice, and the date on which each inventor actually reduced the invention to practice.

This is another area of U.S. law that was amended after GATT.

As noted above, the United States patent system is based on a “first to invent” standard, while most other countries award patents based on “first to file.” Previously, U.S. patent law provided that activities which occurred outside of the United States could not be relied upon to prove a date of invention. Most often this worked to the detriment of foreign applicants because they were severely limited on the activities which they could use to prove a date of invention. However, after the effective dates of this portion of the GATT (and NAFTA) legislation, applicants can rely on activities which occur in World Trade Organization countries after January 1, 1996 to prove dates of inventorship. For NAFTA countries, activities after December 8, 1993 in NAFTA countries can be relied upon. These changes are not retroactive, but instead apply only to applications filed after the above dates.