Bureau of Tobacco, Firearms and Explosives and the TTB.gov
Alcohol and Tobacco Tax and Trade Bureau, U.S. Dept. of the Treasury. Includes links to relevant CFR regulations (generally found in 27 CFR).
United Nations Office on Drugs and Crime (UNODC)
UNODC is a global leader in the fight against illicit drugs and international crime including: prison reform, money-laundering, organized crime, terrorism prevention, etc. Resources include data and analysis.