Pub. L. 90-351, tit. VII, sec. 1203

Sec. 1203. This title shall not apply to— (1) any prisoner who by reason of duties connected with law enforcement has expressly been entrusted with a firearm by competent authority of the prison; and (2) any person who has been pardoned by the President, of the United States or the chief executive of a State and has expressly been authorized by the President or such chief executive, as the case may be, to receive, possess, or transport in commerce a firearm.