Public use and transit: Smoking cannabis in enclosed public areas like restaurants and bars —all the same places where it is illegal to smoke cigarettes—is forbidden. On driving under the influence, Uruguay’s law adopts a “zero toler- ance” policy. The U.S. state laws each set a limit of less than five nanograms of tetrahydrocan- nabinol (THC) per milliliter of blood to drive, but in the South American country any level of detectable THC in the body is enough to deem a motorist impaired.