The United States Patent and Trademark Office (USPTO or Office) amends the rules of practice to expand when certain types of patent applicants and patentees may, subject to other conditions, obtain or enforce a second patent for an invention that is similar (i.e., patentably indistinct) to a first patent. Ordinarily, in examination before the USPTO, any application for a second patent covering such similar invention would be rejected. The rule change is limited to the situation where owners of the first and second patents or patent applications are different but have an agreement to conduct research together (i.e., a joint research agreement). For this limited situation, the rule change would increase the ability to file a document, called a terminal disclaimer, that ties the rights of a second patent to the first patent. Specifically, a terminal disclaimer causes the second patent to limit its enforceable patent term to end no later than the first patent’s term and limits when the second patent can be enforced. The rule change would expand when a terminal disclaimer is permitted to be filed in the joint research agreement situation by eliminating the requirement that the second patent or patent application be filed later than the first patent or patent application. The USPTO also amends its rules of practice to explicitly state existing practices in the rules regarding when certain affidavits and declarations, as well as terminal disclaimers, may be filed.