What must law enforcement do when a driver refuses a breath test?

When a driver refuses a breath test, the law enforcement officer must read the implied consent warning. This is a critical step because, in many jurisdictions, when a person obtains a driver's license, they consent to chemical testing for blood alcohol concentration (BAC). The implied consent law informs the driver that refusing a test can lead to legal consequences, such as license suspension and other penalties.

The rationale behind this procedure is to ensure that drivers are aware of their rights and the implications of refusal. Reading the implied consent warning clarifies to the driver that by operating a vehicle, they have already agreed to take a breath test if requested under suspicion of DUI. This step is essential for establishing that the driver was informed of the consequences, which could be important for later legal proceedings or administrative actions against the driver's license.