Decision makers now frequently seek to deter crime with policies that increase the certainty and celerity of sanction as an alternative to increasing severity. South Dakota's 24/7 Sobriety Program is a novel, large-scale intervention requiring those arrested for or convicted of an alcohol-related offense to abstain from alcohol and submit to alcohol tests multiple times daily. Those testing positive or missing a test receive a swift, certain, and moderate sanction; typically a night or two in jail. To estimate the causal effect of 24/7 on the probability of rearrest or probation revocation for those arrested for a second or third driving under the influence (DUI) offense, we instrument an individual's 24/7 participation with program availability in the county of arrest. We estimate the individual-level probability of rearrest or probation revocation is 13.7 percentage points (49 percent; p = 0.002) lower for 24/7 participants than non-participants 12 months after their DUI arrest. We detect substantive decreases at 24 and 36 months, but the precision of those estimates depends on model specification. These findings provide additional support for applying "swift-certain-fair" sanctions in community supervision. This paper also provides policymakers with evidence for a new approach to reduce criminal activity among those whose alcohol use leads them to repeatedly threaten public health and safety.