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18 U.S.C. 343: PresumptionsText contains those laws in effect through Public Law 119-120 (October 7, 2026).
From Title 18-CRIMES AND CRIMINAL PROCEDURECHAPTER 17A-COMMON CARRIER OPERATION UNDER THE INFLUENCE OF ALCOHOL OR DRUGS
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§343. Presumptions

For purposes of this chapter⁠—

(1)  an individual with a blood alcohol content of .10 percent or more shall be presumed to be under the influence of alcohol; and

(2)  an individual shall be presumed to be under the influence of drugs if the quantity of the drug in the system of the individual would be sufficient to impair the perception, mental processes, or motor functions of the average individual.

(Added Pub. L. 99–570, title I, § 1971(a) , Oct. 27, 1986 , 100 Stat. 3207–59 ; amended Pub. L. 100–690, title VI, § 6473(c) , Nov. 18, 1988 , 102 Stat. 4379 .)

Editorial Notes

Amendments

1988⁠—Par. (1). Pub. L. 100–690, § 6473(c)(1), substituted “.10 percent” for “.10” and struck out “conclusively” after “shall be”.

Par. (2). Pub. L. 100–690, § 6473(c)(2), struck out “conclusively” after “shall be”.