Over the last several years, blood testing in DWI cases has become more common. In the past, if you refused to take a breath test that was the end of it – you were simply processed, and booked into jail. Now, it’s more likely that the officer will request a warrant to get a blood sample. They now have forms where all they have to do is fill in some information, and then fax it to a judge for signature. Many jails now even conduct blood draws right there, and the officer doesn’t have to take the suspect to a hospital. In short, it is far easier to get a warrant to obtain a blood sample, and there is little reason not to do so. There has also been an increase in “no refusal” periods. Generally, these are established during holiday periods. Arrangements are made with judges to “be available” to issue warrants, and if a suspect refuses a breath test the officer will automatically start the process to get a warrant.

            All of this means that NO longer means no. Just because you decline to take a breath test doesn’t mean you aren’t going to be tested. Instead of blowing in a machine, you may end with a needle being stuck in your arm.

Problems with blood testing

            Many people believe that blood testing is more accurate than breath testing. While that may be generally true in theory, it is not true when it comes to blood testing in DWI cases. As with any testing, the validity of the result depends on how the test is doing. If all the proper procedures are not followed, the results are not going to be valid. In a typical DWI case, there are a number of steps that must be followed, which means there are a number of things that can go wrong.

The blood draw and collecting the sample

            The starting point is the blood draw. The process is not as simple as sticking a needle in your arm and drawing blood. For starters, the area where the blood is drawn must be properly cleaned. Iodine or Betadine are generally used since the use of alcohol would introduce alcohol into the sample. Occasionally the person drawing blood may not realize that and use the wrong thing. That is something your lawyer should check, along with the expiration dates of the cleaning solution.

The reason for cleaning the area is to get rid of bacteria. That is important in alcohol testing because there are some bacteria that can actually interact with the sugars in blood and produce alcohol in the test tube. If that occurs, the reading is going to be elevated. The person cleaning the site is taught to start at the site, and clean in concentric circles, moving out. That pushes any bacteria or other material out of the way. It is not proper to simply take the swab and move it back it forth – that simply moves it around, without getting rid of it.

The tubes used to collect blood are vacuum sealed, so that when the needle is inserted in the tube the vacuum will draw blood into the tube. All tubes have expiration dates, which you must check. If the expiration date has expired, the tube should not be used. There are least two reasons for that. The first is that the seal may have been compromised, which means that outside air can get in – which causes contamination. The other reason relates to the chemicals inside the tube. All tubes contain a mix of chemicals which prevent the blood from clotting, and from fermenting. Think of what happens with milk when you leave it out for a few days or several weeks in the refrigerator. Those chemicals also have expiration dates, beyond which they will no longer be effective.

Once the blood is collected, the chemicals must be mixed with the blood. The manufacturers of the tube have specific instructions for how to handle the sample. Generally, they recommend that the tube is inverted 8 times. The tube should never be shaken; doing so can rupture the cells, which can result in an elevated blood alcohol reading. If the chemicals are not properly mixed, clotting or fermentation can occur. It is important to look at the notes of the person who ends up testing the blood to see if there are any notations that suggest the sample may not have been properly collected.

Transporting and storing the sample

Once the blood is collected, it is transported to a lab. There it should be refrigerated – for the same reasons you refrigerate milk and other organic materials which can degrade. There are logs kept of how the sample is stored, and at what temperature, and those logs must be checked to see if there are any issues. You also must look at the chain of custody, and where the sample was before it got to the lab. While the preservatives will work for some period of time, you need to know if the sample was kept in the trunk of a patrol car during the summer for several weeks.

When it comes time to test the sample, it is taken out of the refrigerator, and allowed to come to room temperature. That process is documented – as is everything else that happens at the lab – and should be reviewed. Once the analyst is ready to test the sample, a sample will be removed from the tube, and placed into a vial. That is done by an instrument called a pipette. It is important that the correct amount of blood be placed in the vial, and the pipettes are calibrated to transfer a certain. They have to be calibrated and checked periodically, and those records should be reviewed.

What's next

In the next article, I'll discuss how the blood sample is actually tested. As you can see from this short discussion, there are a number of steps to collecting a blood sample to test. At each step there things which must be done, and done correctly. These are not technical or "nitpicky" requirements; they are there to ensure the end result - which is the result used against you in court, is reliable. This is not like changing the oil in your car. Fortunately, there are procedures that require the steps to be documented, so that the analyst - and anyone relying on the test - will know everything was done properly. Those documents are kept at the lab, but not generally provided to the District Attorney or the police department. Your lawyer must ask for them.

If you want more information on this subject, get a copy of our DWI Survival Guide. If you need help with a DWI case and want to talk with an experienced attorney who knows the issues, give us a call at (254) 296-0020.

Walter Reaves
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Criminal Defense Attorney Walter Reaves has been practicing law for over 35 years.