NOTE: The Organisation for the Prohibition of Chemical Weapons, “Article II. Definitions and Criteria.” at Paragraph 9,“Purposes Not Prohibited Under this Convention”, subparagraph (d) specified “Law enforcement including domestic riot control purposes.”
Aside from this being a defense support to civil authorities (DSCA) mission in support of law enforcement, consider Executive Order 11850–Renunciation of certain uses in war of chemical herbicides and riot control agents which was signed on April 8, 1975, by President Gerald Ford, restricting the use of herbicides, and riot control agents, including tear gas. Each and every use would require the explicit approval.
On April 11, 2007 Joseph Benkert informed the Senate Armed Services Committee that the Bush Presidency felt it could reinterpret the Executive Order and loosen the restriction on the use of gas as a riot control agent.