When someone is arrested for driving under the influence (DUI) or driving while intoxicated (DWI), the state’s per se intoxication law may apply. Per se intoxication laws state that if a driver is stopped by the police for suspected impaired driving and has a blood alcohol concentration (BAC) of 0.08% or higher, that will be enough evidence to establish that the driver is intoxicated.

What this means is that the prosecution will only need to show that an individual had at least a BAC of 0.08% to get a conviction. If the police officer did not perform any field sobriety tests or take any other measures to establish intoxication, those facts will be irrelevant for prosecution under the per se intoxication law.

However, it is possible for any driver to be charged with DUI, absent evidence of per se intoxication. In many states, a driver can be convicted of DUI based on driving while impaired, regardless of whether their BAC was .08% or not. In most cases, the arresting officer must provide evidence of impaired driving to the court. For instance, visible swerving or blowing through stop signs, and/or the slurring of words, or failing field sobriety tests would generally suffice.

The DUI per se laws also do not address when someone is driving under the influence of illegal drugs. This can be more difficult to prove. However, some states do have separate per se intoxication laws addressing driving while under the influence of illegal drugs. The states vary in whether these laws set an intoxication limit or employ a zero tolerance policy.

Also keep in mind that any person under the legal drinking age of 21 years old cannot have any alcohol in their system while driving in any state. This zero tolerance DUI policy applies to all underage drivers, and makes even a trace amount of alcohol in the bloodstream illegal.

How were Per Se Intoxication Laws Created?

Though DUI per se laws may seem arbitrary, it was through the lobbying efforts of Mothers Against Drunk Driving and scientific opinion to develop a standard of safety. These efforts considered the BAC level that would classify a driver as being under the influence. 

Originally, scientific opinion was that a BAC level of 0.10% should be considered under the influence. However, the National Highway Traffic Safety Administration lowered that level to 0.08%. All states have adopted the 0.08% limit as a condition made by the federal government to receive federal transportation aid.

What Factors are Considered in Issuing Penalties for Per Se DUI Charges?

After being convicted for a per se DUI, the defendant will be sentenced and face penalties like with any other type of DUI charge. While all states have a DUI per se law, they differ in the range of penalties that a driver would receive for a DUI conviction. Legal consequences like heavy fines, license suspension, probation, jail or prison time, home confinement, ignition interlock, random alcohol tests, and community service are all common DUI penalties.

Remember that the exact penalties will depend on your state’s laws, the judge, and circumstances surrounding the arrest. Courts universally use some or all of the following factors when determining a defendant’s consequences for a DUI charge:

  • Prior conviction history;
  • Prior history of DUIs (for instance if they are a repeat DUI offender);
  • Whether serious bodily injury or death was a result of the DUI charge;
  • Whether property damage occurred;
  • Whether the driver was using the car or vehicle for commercial purposes;
  • The driver’s BAC level;
  • Whether or not the driver was of legal drinking age at the time of arrest; and/or
  • Whether or not a child or minor was in the driver’s car at the time of the incident.

Penalties for first offenses that do not cause injury or death to another person are generally more lenient than a repeat DUI offender, or when the crime harms another person.

Are there any Defenses to Per Se Intoxication Laws?

While there is less room for argument on a per se intoxication charge, the defendant may still be able to assert some defenses. This includes the following:

  • Challenging the validity of the test results;
  • Claiming that the machine collecting the results was operating improperly; and
  • Challenging the DUI arrest procedure.

Whether these or other defenses are available will depend on the specific circumstances surrounding the defendant’s case and state DUI laws.

Should I Hire a DUI Lawyer for Per Se Intoxication Violations?

DUI per se charges are quite serious and can be harder to fight in court. As such, if you are facing criminal charges you should consider contacting a local criminal lawyer specializing in DUIs immediately. 

Every state has its own DUI laws and sentencing requirements, and an experienced lawyer can advise you of your rights, build your case, and represent your best interests in court. A lawyer can also advise you about any defenses you may have to try and get rid of your charge or lessen the penalties.