The legal BAC limit in Cranston is 0.08 percent for adult drivers 21 and over, the same Rhode Island state law that applies across all RI municipalities. Drivers under 21 face a 0.02 percent zero-tolerance limit. Commercial drivers face a 0.04 percent limit while operating commercial vehicles. Being at or above these thresholds is per se DUI under Rhode Island law. Cranston police can also charge DUI below 0.08 if other evidence (driving behavior, field sobriety performance, statements at the scene) supports impairment, though these cases are harder to prosecute without a per se BAC.
