If a person is being charged with Driving Under the Influence (DUI) or will be charged with a DUI pending proof of blood alcohol content (BAC), then a blood test can be used. A blood test takes a sample of the person’s blood and measures the amount of chemical substances in their blood. These tests are generally not given at the scene, since only a qualified person can administer the test. Blood tests are quite accurate since it can pick up traces of any substance a person has ingested. 

Each state has different regulations as to:

  • Who is qualified to give a blood test?
  • How these tests are taken?
  • How these tests are transported?
  • How these tests are analyzed?

Who is Qualified to Administer a Blood Test?

Qualified individuals will vary from state to state. Generally, a person who is under the supervision of a qualified physician or has been licensed in phlebotomy will be deemed capable of administering blood tests.

How Do Blood Tests Work?

A qualified technician must take all DUI blood samples. If the police do not have a qualified person to do the blood test and do not take you to one, then they cannot perform a blood test on you. 

The police must also obtain a warrant for your blood even though you are required to consent by state law. Police can get the warrant pretty fast as it is a routine part of a DUI arrest.

Before the blood is drawn, the police is required to explain the procedure to you and explain the penalties for refusing. Then the police will ask you to submit to the blood test. If you disagree or delay in doing the blood test, it will be counted as a “refusal that can turn into jail time and a longer license suspension to your regular DUI penalties

You are allowed to ask for a different type of test, such as a breath test or urine test, but if those tests are not available, you must submit to the blood draw.

After you agree on doing the blood test, the technician will swab your arm and use a needle to draw the blood and will conduct the results of the test. 

How Reliable are Blood Tests?

Blood tests are more reliable than a Breathalyzer tests. This is because the blood test takes the exact chemical content of your blood at the time of the draw. Blood tests are also considered to be a lot more reliable than a breath test since the breathalyzers are not properly functioning at the time of the test and samples must re-tested multiple times to verify the results of the first test. 

There are some reasons why blood tests are unreliable and these reasons include:

  • Blood sample was taken too long after the initial arrest;
  • Blood sample was contaminated;
  • Blood sample was improperly stored;
  • A qualified technician did not do the blood test; and/or
  • Blood sample was transferred improperly.

Am I Required to Take a Blood Test If Asked To?

Every state has "implied consent" laws; if you drive, you are “consenting” to being subject to DUI or DWI testing upon being suspected of DUI or DWI. The penalties for not cooperating vary from state to state. 

For example, some states automatically suspend your license if you refuse to take a blood test, while other states simply cite it as uncooperative behavior.

Can I Challenge a Blood Test?

Yes. You or you lawyer can challenge the legitimacy of the blood test on any of the grounds above and also challenge the procedures conducted by the police officer during the time of the test. 

If the reason for the blood test was improper or the correct procedure for the blood test was not followed, then it is possible for the evidence of the blood test to be thrown out of court. Meaning that the blood test results cannot be used to convict you for your DUI charge.

Do I Need a Lawyer?

Blood tests are notorious for being reliable. If you have been subject to a blood test, and are facing prosecution for a DUI or DWI, you should consider contacting a criminal defense lawyer to help you understand your rights and defenses.