No provision of this subchapter shall be construed as indicating an intent on the part of the Congress to occupy the field in which that provision operates, including criminal penalties, to the exclusion of any State law on the same subject matter which would otherwise be within the authority of the State, unless there is a positive conflict between that provision of this subchapter and that State law so that the two cannot consistently stand together.
21 U.S. Code § 903 - Application of State law
This subchapter, referred to in text, was in the original “this title”, meaning title II of Pub. L. 91–513, Oct. 27, 1970, 84 Stat. 1242, as amended, and is popularly known as the “Controlled Substances Act”. For complete classification of title II to the Code, see second paragraph of Short Title note set out under section 801 of this title and Tables.