37 CFR §205.23

1. (a)
   1. (1)If a Copyright Office employee is authorized to give testimony in a legal proceeding, the testimony, if otherwise proper, shall be limited to facts within the personal knowledge of the Office employee. An Office employee is prohibited from giving expert testimony, or opinion, answering hypothetical or speculative questions, or giving testimony with respect to subject matter which is privileged. If an Office employee is authorized to testify in connection with his or her involvement or assistance in a proceeding or matter before the Office, that employee is further prohibited from giving testimony in response to an inquiry about the bases, reasons, mental processes, analyses, or conclusions of that employee in the performance of his or her official functions.
   2. (2)The General Counsel may authorize an employee to appear and give expert testimony or opinion testimony upon the showing, pursuant to § 205.3 of this part, that exceptional circumstances warrant such testimony and that the anticipated testimony will not be adverse to the interest of the Copyright Office or the United States.
2. (b)If an Office employee is authorized to testify, the employee will generally be prohibited from providing testimony in response to questions which seek, for example:
   1. (1)To elicit information about the employee's:
      1. (i)Qualifications to examine or otherwise consider a particular copyright application.
      2. (ii)Usual practice or whether the employee followed a procedure set out in any Office manual of practice in a particular case.
      3. (iii)Consultation with another Office employee.
      4. (iv)Familiarity with:
         1. (A)Preexisting works that are similar.
         2. (B)Registered works, works sought to be registered, a copyright application, registration, denial of registration, or request for reconsideration.
         3. (C)Copyright law or other law.
         4. (D)The actions of another Office employee.
      5. (v)Reliance on particular facts or arguments.
   2. (2)To inquire into the manner in and extent to which the employee considered or studied material in performing the function.
   3. (3)To inquire into the bases, reasons, mental processes, analyses, or conclusions of that Office employee in performing the function.
3. (c)In exceptional circumstances, the General Counsel may waive the limitations set forth in paragraph (b) of this section pursuant to § 205.3.