(a) No license or other authorization contained in this part or otherwise issued by or under the direction of the Secretary of the Treasury pursuant to section 3(a) or 5(b) of the Trading With the Enemy Act, as amended, or section 620(a), Pub. L. 87-195, or Proclamation 3447, shall be deemed to authorize or validate any transaction effected prior to the issuance thereof, unless such license or other authorization specifically so provides.

(b) No regulation, ruling, instruction, or license authorizes a transaction prohibited under this part unless the regulation, ruling, instruction, or license is issued by the Treasury Department and specifically refers to this part.