One of the basic requirements for obtaining a patent is that the invention must be new. If the same invention has been patented before, or even written about or used for a certain amount of time before a patent is applied for, it will not be eligible for a patent.
Sometimes, two or more inventors seek to patent the same invention at the same time, or an inventor will apply for a patent for an invention that is already patented. In such a case, because the invention may only be the subject of one patent, the United States Patent and Trademark Office (USPTO- will determine who was the first inventor, and thus who is entitled to the patent, by way of a proceeding called an “interference.” In the case of applicants, the need for an interference may be determined by the USPTO itself, or it may be requested by one of the applicants. In addition, if an applicant believes that he or she is entitled to a patent that has been granted to another inventor, the applicant may request an interference. In requesting an interference, such an applicant must submit evidence that provides an initial showing that the applicant is entitled to the patent notwithstanding its prior issue to another inventor. An interference is not available after one year has passed since the filing of the earliest of the conflicting applications or the issuance of the existing patent, whichever the case.
Interferences are decided by the U.S. Patent and Trademark Office’s Board of Patent Appeals and Interferences (BPAI). The USPTO has no jurisdiction over disputes between patentees; thus, at least one of the parties to an interference must be a patent applicant. The determination of who is entitled to the disputed patent will depend on the evidence submitted in support of each applicant or patentee’s claim. The BPAI will attempt to determine when each party conceived of the invention as it would actually take form and when each party actually created a physical embodiment of the invention, whether it be a machine, a process, a material or other patentable item. Actually creating the subject of the patent is called reducing the invention to practice. The law treats a proper patent application that fully describes the invention as the legal equivalent of reducing the invention to physical form, so in the absence of evidence of earlier reduction to practice, the application date will be considered the date of reduction to practice.
Generally, the inventor who conceived of the invention and reduced it to practice first will be found to be entitled to the patent. However, it is possible that an inventor could conceive of an invention first but be the second to reduce it to practice. Because the primary objective of patent law is the advancement of science and technology rather than rewarding inventors, and because patent law is designed to encourage disclosure of inventions for the benefit of public knowledge in a timely manner, whether such an inventor will be found to be entitled to the patent depends on whether that inventor was reasonably diligent in transforming the conceived invention to a working machine or process or finished material. If a lack of diligence is found–for example, if it is clear that the first inventor to conceive of the invention made an effort to conceal the invention–it is possible that the inventor who conceived of the invention later but diligently worked to create a finished product will be entitled to the patent.