Which of the following methods can be used to correct inventorship in an issued patent?

The method of correcting inventorship in an issued patent is through a Certificate of Correction. This process is governed by specific provisions under the Patent Act, which allows for the correction of errors in the patent document, including errors related to inventorship.

When a Certificate of Correction is requested, it must be for an error that is of a minor nature or an inadvertent mistake. This typically includes situations where a named inventor should not have been listed or where an actual inventor was omitted. The USPTO provides a formal procedure for submitting a request for a Certificate of Correction, which can streamline the rectification of such errors without the need to file a new application or go through extensive legal hurdles.

The other options, while they may be relevant in different contexts (for instance, submitting a new application may be needed for different issues or claims), do not specifically focus on the procedure established for correcting inventorship. Letters to the USPTO could theoretically communicate a request, but they are not a formal or adequate mechanism for making corrections to patent documents. Oral argument before the board typically pertains to appeals or interferences, which do not directly relate to correcting inventorship in an issued patent.