Last Updated on January 30, 2024 by Asfa Rasheed

The Supreme Court has made it clear that if someone does not consent to a breath or blood test for purposes of a drunk driving investigation, police must have probable cause and obtain a search warrant before forcing a sample. If they fail to follow this protocol, the evidence could be tainted and excluded from your case. Contact an experienced DUI attorney if you have questions about a blood draw or have been arrested on suspicion of DWUI. 

Refuse the Blood Draw 

In some situations, the police may wish to conduct a blood test to find out your BAC (blood alcohol content). This information can be used against you in court. If you have been pulled over for suspicion of DUI and the officer asks you to submit to a breath or blood sample, remember that the Fifth Amendment protects your right against self-incrimination. However, you can also refuse a blood test without breaking the law. If a member of law enforcement wants to take your blood forcefully, they must first get a DUI blood draw warrant from the court. The Supreme Court has ruled that forcing you to submit to a post-arrest blood sample without a warrant violates your Fourth Amendment rights against unreasonable search and seizure. To obtain a warrant for your blood, the officer must have probable cause that you are driving under the influence. In addition, the court must consider the procedure reasonable – officers can’t just hold you down and jab a needle into your arm. They must use sanitary procedures and only withdraw what is necessary for the test. 

File a Motion to Suppress the Blood Evidence 

As soon as possible, your attorney should examine the evidence that could be used against you and determine whether there is a reason to file a motion to suppress. This is a request that the court exclude specific evidence from your case because it was not legally gathered. The defense lawyer will argue that the forced blood draw violated your Fourth Amendment rights by not having probable cause and did not meet any of the exceptions to the warrant requirement. This will often result in the court excluding this evidence. This can dramatically weaken the prosecution’s case and make it much harder for them to prove you guilty beyond a reasonable doubt. This is why it is essential to hire a skilled DUI attorney to examine the evidence and determine whether there are grounds to file a motion to suppress. In addition to the blood test results, your attorney will examine all other physical evidence collected during the investigation. This includes any field sobriety tests or statements that you made. They will also scrutinize the affidavit for errors, lies, or issues that could invalidate the warrant or make the evidence unreliable. The police are required to keep a written chain of custody for all physical evidence, so if this is not maintained correctly, it can also be a ground to exclude the evidence from your case. 

Hire an Attorney 

Blood tests are a crucial piece of evidence in DUI cases. Under Illinois’ implied consent law, drivers give police the right to have their blood or breath tested for alcohol content after they are arrested for DUI. However, to draw a blood sample, officers must have a search warrant from a judge or magistrate. This is a legal process that takes time. During this time, your BAC could dissipate and lose its reliability. Police must write an affidavit explaining why they need the blood sample and stating that they have probable cause to believe they are driving under the influence. These affidavits must be reviewed and checked for errors before they can be used as evidence in court. Your attorney can look for issues such as weak probable cause, erroneous statements in the affidavit, and improper warrant execution. In a blood test case, your lawyer will also examine the chain of custody for the blood sample and the lab’s equipment. They will review maintenance and calibration logs as well as certification records to find any potential problems that may have occurred. These problems might lead to cross-contamination, sampling mistakes, or faulty testing results that can be used against you in your DUI case.