Under what condition can a substitute specification be filed as a matter of right?

A substitute specification can be filed as a matter of right before the issue fee is paid because, at this stage, the application has not yet entered the final phase of prosecution. The rules set forth by the USPTO allow for amendments and corrections to be made to the specification up until the issue fee is paid, providing an opportunity for applicants to clarify or modify their claims and descriptions to ensure their invention is accurately represented and protected.

This principle helps maintain the integrity of the application process, allowing applicants to address any potential issues that may have arisen during examination. Once the issue fee is paid, the application is generally considered to be in its final form, and no further amendments are allowed without special circumstances justifying a change. Consequently, the ability to submit a substitute specification ceases at that point, reinforcing the importance of making necessary modifications beforehand.