How a Criminal Defense Attorney Can Challenge a DWI Checkpoint

Law & Legal

The Supreme Court has ruled that DUI checkpoints are legal but defense lawyers can challenge the way they are set up and run. They look at how much advance notice was given and whether motorists were able to safely avoid the checkpoint.

It is also illegal to select drivers based on their age, race, sex or other factors. An unbiased protocol needs to be in place for which vehicles are stopped. Visit the website.

Probable Cause

In the state of Missouri, law enforcement agencies can set up DWI checkpoints to investigate drivers who may be driving under the influence. These roadblocks must meet certain criteria for them to be considered legal by the U.S. Supreme Court, including having proper procedures in place for conducting the stop. Criminal defense attorneys can scour the details of these stops to look for any violations of constitutional rights.

For a DWI checkpoint to be valid, police must have probable cause that the driver has been drinking, either through initial observations, field sobriety tests or statements by the driver. Without this, the stop and subsequent arrest could be challenged in court.

If stopped at a DWI checkpoint, you should obey all instructions given to you by the officer, but you are not obligated to give any information that could incriminate you. Avoid answering questions such as “Have you been drinking tonight?” unless you can truthfully say no.

Refusal to Submit to Field Sobriety Tests

A criminal defense attorney may be able to help you fight DUI charges stemming from a sobriety checkpoint in Missouri. The Supreme Court has ruled that these checkpoints do not violate the Fourth Amendment rights of drivers, but they must be conducted correctly. A skilled attorney can scour the details of how the checkpoint was set up and determine if any of your rights were violated during the stop.

When approached by officers at a DUI checkpoint, you should remain calm and polite. Do not answer any questions, unless you can truthfully say no. Even the slightest admission of drinking could lead to an arrest.

During the encounter, an officer will ask to see your driver’s license and registration. They will also want to know how much you have had to drink. If they believe you are intoxicated, you will be asked to perform a field sobriety test. These tests include the HGN (eyes), Walk and Turn, and One Leg Stand. Refusal to submit to these tests can result in an automatic one-year suspension of your driving privileges.

Breathalyzer Tests

The Breathalyzer tests that are performed by the officers at these checkpoints are incredibly flawed. These machines use a limited range of wavelengths to analyze breath samples and only return results based on the assumption that the unknown substance is ethanol consumed by the driver. Unfortunately, many different substances absorb infrared light at the same wavelengths as ethanol, so these machines will often mistake them for BAC levels.

When police ask you to blow into a portable breath testing device at a DUI checkpoint, they must read the driver Missouri’s Implied Consent Admonishment (similar to Miranda rights) and allow them 20 minutes or more to call their attorney before administering the test. If the officer does not follow this protocol, they are violating the driver’s constitutional rights and they could face a criminal case.

In Missouri, you are required to provide a breath or saliva sample for BAC, and refusing will result in an automatic one-year license revocation. It is also illegal for the police to search your vehicle without probable cause or your permission.


If officers at a DUI checkpoint find probable cause that you are driving under the influence, they may ask to search your vehicle for evidence of alcohol or drug use. If they find odor of alcohol, open or visible containers of beer or other alcoholic beverages, or slurred speech, they can then detain you to ask questions and perform field sobriety tests.

However, police must follow certain guidelines to conduct a DWI checkpoint properly. These include announcing the time and location of the checkpoint, posting warning signs, and using safety measures. If police fail to follow these standards, it can be used in your defense that the checkpoint was unconstitutional.

Whether you have been stopped for routine questions, or for refusing to take a breathalyzer test, it is important to speak with your Missouri DWI lawyer. Your attorney can help you mount a strong legal defense. The Supreme Court has ruled that DUI checkpoints do not violate your constitutional rights if they are conducted correctly.