When the police suspect a driver is inebriated, chemical testing to determine their blood alcohol concentration (BAC) is almost certainly going to be performed.
Tests that evaluate a driver’s BAC can help the police determine if a driver has exceeded the statutory limit to establish “per se” or legal intoxication. However, even when a driver’s BAC is below the limit, a positive BAC may still lend credence to the prosecutor’s claim that the driver was too impaired to be behind the wheel.
Blood, breath and urine are the keys
Typically, officers will use a “breath test.” Many drivers are somewhat familiar with so-called “breathalyzer” devices that can calculate their blood alcohol content from the amount of alcohol molecules in their breath. While the police often have small, handheld devices with them at the roadside, these preliminary breath tests (PBTs) are generally not admissible in court.
After a tentative judgment has been made and the driver has been arrested, the breath test will generally be conducted at the police station or jail using a stationary machine. That test result is typically used in court.
The other two types of field sobriety tests are done using blood tests and urine tests. These tests must be conducted by medical professionals and are rarely used. They may require either the consent of the driver or a warrant from a judge to gather the bodily fluids.
BAC limit in Missouri
A driver is considered drunk if their blood alcohol content exceeds Missouri’s legal limit. Missouri has several BAC limits, including the following:
- 21 years of age or older: 0.08%
- Younger than 21 years of age: 0.04%
- Commercial drivers: 0.02%
Drivers who exceed the applicable legal limit can lose their license and face jail time and fines. Commercial drivers who exceed the legal limit can potentially lose their professional license. If a driver exceeds a BAC of 0.15%, they may face much harsher criminal punishments due to their higher level of intoxication, since that puts others at additional risk.
Professional legal guidance can help drivers who are facing DUI charges regardless of their situation and BAC readings.