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How Does A Blood Draw Work For A DUI?

Sabah Khalaf
8 minute read

If you are pulled over for driving under the influence, you will be offered an opportunity to take the State of Oklahoma’s test. This is a test designed to determine your blood alcohol content. This test can be either a

(1) breathalyzer test; or

(2) blood test.

Most people are familiar with a breathalyzer test, but the blood test is a little more foreign. We will explain how a blood test works, how it is different from a breathalyzer test, and how the differences could impact your criminal charges.

What is the State’s test?

The State’s test is designed to determine whether you have been driving under the influence (DUI). There are two types of tests: a blood draw and a breathalyzer test.

A breathalyzer is a machine which you blow into, that indicates your blood alcohol content (BAC). A breathalyzer test is often administered on the side of the road by your vehicle, but the official State's test will be administered at the police station or jail, specifically on an Intoxilyzer 8000.

A blood draw is administered at a hospital by a nurse. It is done the same way any other blood draw is done, by taking a blood sample from your body and then sending that sample to a lab. This does not provide immediate results, and can sometimes take a few months. A blood draw, however, provides much more information.

A blood draw not only provides your BAC, but also provides information about all other substances within your system. This includes illegal controlled substances, such as methamphetamines and heroin, as well as legally obtained substances, such as marijuana or pain medication. The results of your blood draw can affect whether or not you receive criminal charges. For example, if a blood draw shows that your BAC is a .05, which is under the legal limit, but your system also contains marijuana, you will be charged with a DUI.

What is the legal limit for alcohol?

The legal limit for alcohol is a .08 BAC. However, you can be charged with driving while impaired (DWI) if your BAC is a .06 or higher. If you have a BAC of .15 or higher, you can be charged with an aggravated DUI.

What is the legal limit for marijuana?

There isn’t a legal limit for marijuana. Any amount of THC in your system is an illegal amount for purposes of a DUI. The same can be said for all other controlled substances. Any amount of an illegal substance, such as heroin or methamphetamine, is an illegal amount for the purposes of driving.

This is important to emphasize: You can legally use marijuana in the State of Oklahoma, but if it is in your system while driving, you will receive a DUI. This is true even if you are no longer experiencing the effects of marijuana.

Does marijuana show up with a breathalyzer?

No, breathalyzers will not show marijuana in your system. Breathalyzers are designed to measure alcohol only. While law enforcement is in the process of developing a breathalyzer that will detect marijuana in a person’s system, it has not yet been approved for use as evidence in a criminal court.

Do I have a choice in which test I can take?

No, you don’t. The arresting officer will ask your permission to take the State’s test, but they will not give you a choice between a breathalyzer or blood test. The officer will make that decision themselves. An officer will ask if you would like to take the State’s test, and once you say yes, they will either administer the breathalyzer or take you to a hospital for a blood draw.

While you generally can't choose which test to take, If a breathalyzer test is offered and you take it, you can request an independent blood test and the officer must take you to get one.

Can I refuse to take the tests?

Yes, you can. Officers will ask if you would like to take the State’s test, and you can say no to both tests. If you have said yes to this question because you wanted to take a breathalyzer test, and an officer takes you to a hospital for a blood draw, you can say you don’t want a blood draw and no longer wish to take the State’s test. While this can be used against you in trial, an officer can’t force you to take the test.

If I am unconscious, can an officer take my blood without my consent?

No, an officer can’t take your blood for testing without your consent. While this may initially seem like an outlandish scenario, it is a more common issue than you would expect. Many people end up unconscious after DUI accidents, or occasionally pass out in their vehicles due to intoxication. If an officer finds you unconscious, they cannot then take you to a hospital and draw your blood without your consent. This is true even if your blood must be drawn for medical treatment. The officer can’t take a sample of the blood for testing.

The Case That Established The Rules

The case that established this rule is called Stewart v. State. In the case, the defendant was driving while under the influence. He stopped his vehicle in the middle of the lane, causing an accident that led to the serious injury of three people and death of two others. The defendant was transported to the hospital, alongside the other victims, for treatment of his injuries. During treatment, a state trooper instructed a registered nurse to draw the defendant’s blood and submit it for testing. This occurred while the defendant was unconscious and the trooper did not have the defendant’s permission, nor did he have a search warrant.

The blood test results confirmed that the defendant had methamphetamine and marijuana in his system. The defendant argued this was a violation of his constitutional rights, specifically his protection against unreasonable searches and seizures. While most people, correctly, think this applies to searches of your home or vehicle, it also applies to searches of your person. The court agreed with the defendant’s argument, and found that this right also applies to the blood inside your body. Therefore, the trooper needed either a search warrant OR the defendant’s permission to test the defendant’s blood.

Can an officer get a search warrant for my blood?

Yes, an officer can get a search warrant. There is a specific legal process for getting a search warrant, and it must be approved by the judge. This can take a while, which is why officers usually just ask for your consent to draw blood. Typically, judge’s don’t grant search warrants for basic DUIs. They normally only grant a search warrant when a person is killed or very seriously injured. Regardless, search warrants are rarely obtained while the evidence is fresh enough to be admitted at trial.

If I decline the State’s test, does this mean I can’t be charged with a DUI?

No. Just because you refuse to take the State’s test doesn’t mean you won’t be charged. A refusal of the state’s test can be admitted as evidence, and can be used to show that you were most likely intoxicated at the time. However, the State has the burden of proof, which means they must show that you were intoxicated. It is not up to you to show that you weren’t intoxicated.

The Bottom Line

If you are pulled over for a DUI, you will be offered the opportunity to take the State’s test. This can be either a blood draw or a breathalyzer test, but you will not have the opportunity to choose between these two options. Regardless of the type of test, you do have a right to refuse the test and it can’t be forced upon you without your consent or a search warrant.