19 U.S.C. § 3201
Authority to grant duty-free treatment
The President may proclaim duty-free treatment (or other preferential treatment) for all eligible articles from any beneficiary country in accordance with the provisions of this chapter.
( Pub. L. 102–182, title II, § 202 , Dec. 4, 1991 , 105 Stat. 1236 ; Pub. L. 107–210, div. C, title XXXI, § 3103(c)(1) , Aug. 6, 2002 , 116 Stat. 1033 .)