When a police officer arrests a driver for suspected driving while intoxicated (DWI), they perform a breath alcohol test to determine the driver’s blood alcohol concentration (BAC). Under Texas implied consent law, by driving on a public road, a driver automatically agrees to a breath or blood test if lawfully arrested for suspected drunk driving.
Breath alcohol testing should meet certain techniques and methods for the results to be valid. These include:
Operator certification
Any trained law enforcement officer who observes signs of intoxication in a driver and conducts the initial stop can administer a roadside breath test and standardized field sobriety tests. These roadside tests are voluntary with no legal penalty for refusal. Officers use these tests to build probable cause for an arrest.
If a driver fails the roadside test or refuses the test and an officer uses other evidence to show intoxication, the driver will be arrested.
After arrest, the officers can request the driver take a more reliable breath test. This must be conducted by an operator certified and authorized by the Texas Department of Public Safety (DPS) to use approved equipment. Refusing this will usually have legal consequences due to drivers having given their “implied consent” to it when they get behind the wheel.
15-Minute observation period
An operator should continuously remain in the presence of a driver for at least 15 minutes immediately before the test. They should exercise reasonable care to prevent the driver from placing any substances in the mouth.
The reference system
A breath test machine must use a reference system that tests its accuracy against a known alcohol standard in conjunction with a driver’s analysis. The results from the reference system must be within plus or minus 0.01g/210 L of the expected value.
When the right procedures are not followed, the results of alcohol testing can be challenged. Get more information to know how to defend yourself against a DWI charge.