D.C. Code § 44-712: Terms of Congressmen as trustees or directors of certain corporations or institutions.

In all cases where Members of Congress or Senators are appointed to represent Congress on any board of trustees or board of directors of any corporation or institution to which Congress makes any appropriation, the term of said Members or Senators, as such trustee or director, shall continue until the expiration of 2 months after the 1st meeting of the Congress chosen next after their appointment.