What is the “first to invent” rule?

The “first to invent” rule relates to patent priority.  To understand this, let’s suppose that Inventor A invents a Gadget in 1990 and files a patent application in 1992. Meanwhile, Inventor B invents the same Gadget in 1991 (after Inventor A invented his) but files his patent application that same year, in 1991 (before Inventor A filed his patent application). So Inventor A invented the Gadget first, but Inventor B filed his patent application first. The issue of who gets the patent is the issue of “patent priority.”

In the United States, the issue of patent priority is determined by the so-called “first to invent” rule. So in the above example, because Inventor A invented his Gadget first, he will get the patent, even though Inventor B filed his patent application first. Most foreign countries, however, use an alternative rule called the “first to file” rule. This rule focuses on the filing of the patent application, rather than on the date of invention. So in the same example under this rule, Inventor B would get the patent because he filed first, even though Inventor A invented his Gadget first.

It should be noted that Congress has discussed amending the United States patent laws so that the issue of patent priority is decided by the “first to file” rule used by most other nations, thereby harmonizing United States patent law with the rest of the world’s patent laws.