Blood vs Breath Tests in Fort Worth DWI Cases

Under Texas law, the arresting officer can choose to request a breath test or a blood test from a person at a DWI stop. Quite often, officers prefer to do a breath test, because they have the machine right there at the police department, it’s quick, and you get a result right away. Now, they can choose to request a blood anytime they want instead of breath, and since a blood test, when it’s properly administered, is much more reliable and properly conducted and everything else, that would be the preferred method, yet the officers can choose to ask for breath instead.

It’s basically the officer’s choice of whether to ask for breath or blood. Sometimes they’ll ask for breath, and if the person refuses that, they then can choose to ask for blood if they want. Perhaps the person agrees to the blood test when they wouldn’t have agreed to the breath test, or say the officer chooses to ask for a blood test but the person doesn’t like needles, doesn’t like having their blood drawn from their body, so they refuse that. The officer could choose to then ask for a breath test, but then the officer may not, and could choose to say that the person is just refusing to cooperate. Sometimes, police departments will have a weekend or a holiday where they decide that if any person refuses the breath test and/or refuses the blood test, that they will get a warrant to draw the person’s blood.

Implications of Blood and Breath Tests

It means that if a person refuses a blood test, then the officer can apply to a magistrate or a judge for a warrant which allows the officer to draw the blood from a person even against their will. They could actually tie a person down, force them and draw the blood against the person’s will, but that’s only with a warrant. Frequently these warrants are issued by a judge without legally sufficient reason because it has to be supported by an affidavit which sets out legally sufficient reason for the judge or the magistrate to issue the warrant. We’re frequently able to show that the warrant was an illegal warrant, not supported by a sufficient affidavit, and we can keep the blood from being used against our client because of that reason. An officer can ask for a warrant anytime they want, anytime a person refuses, but frequently police departments will only do that under certain circumstances, say they are having a holiday, or a weekend that they call a no refusal weekend.

If a person refuses breath or blood, then they’ll apply for a warrant. But they can do this any time of the year, they don’t have to wait for one of these holidays or special weekends because they can always go to a judge or a magistrate. There are judges and magistrates who are on duty every day of the year. But what we find is frequently when a person refuses the breath or blood test, the officers don’t choose to get a warrant. So the officers choose not to get evidence that they could when it’s the government and the officers who have the burden of proof of getting the evidence which proves our client guilty.

It can cause a jury to have reasonable doubt when they hear that the officers chose not to get a warrant when they could have. There are other times when a person refuses, that the officer’s procedure states that they must apply for a warrant. An example of this is a situation where a person has been killed or possibly injured and/or taken to the hospital. In this situation, the law acknowledges that blood tests are better and mandates that an officer take a blood sample or apply for a warrant if the person refuses. Many officers’ procedures are that they must apply for a warrant in those situations. So what we know is that they can do this any time of the year if they want, but frequently they just don’t want to, and they choose not to take the time or the effort to get the warrant. If a person has two previous DWI convictions so that a third DWI conviction would be a felony, in those situations, the officer’s procedures normally is that if a person refuses breath or blood tests, that the officer must apply for a warrant.

The Accuracy of Blood Tests

That can depend from one lab to the next, and they all have a margin of error that they will disclose if they are required to. They are required, during cross-examination, to disclose their margin of error or their error rate. Sometimes, we find that the blood test result, which is close to the limit, is actually maybe below the limit when you consider their margin of error. So the accuracy of these tests is not, even when properly done, 100 percent. It may be 98 percent, or it may be even lower than that. This is if everything is done properly. If we have any possible procedures that were not properly followed or any possible contamination, then we can see how the result is not even close to that reliable.

Defense Against Blood Tests in Fort Worth

Frequently we can show that the officer, the blood draw technician, or the lab analyst didn’t follow proper procedures, or the blood test record itself shows that it wasn’t properly analyzed. Often we can cast doubt on it in one of those ways. We can cast doubt on the reliability or the accuracy of the blood test, just by showing the evidence that the person was obviously not intoxicated, and not consistent with whatever level the blood test shows. That alone can cast doubt on the blood test result. Showing jury how easy it is for human error to be involved in a situation, such as misplacement of the vial in the testing machine, can cause the wrong result to be attributed to a client. Just with those things alone, the jury can understand how a blood test over the limit doesn’t prove a person is guilty. The jury must still be convinced beyond a reasonable doubt that the blood test was done properly, that the result was accurate, and that whatever that result was, shows that the person was actually over 0.08 at the time of driving.

That’s another defense, because the blood draw is never done at the time the person was driving. However, intoxication must be at the time of driving. So say the blood draw is taken one hour after the person was pulled over, one hour after they were actually driving, and the blood test was over the legal limit, 0.09. Even if it was done properly and even if the result was accurate, that does not necessarily prove that the person was over 0.08 at the time of driving. In fact, what frequently happens is people have something to drink and then immediately leave the location, the restaurant, the bar, the friend’s house or whatever and then they are promptly pulled over.

The alcohol that they drank right before they left is not in their system yet, that alcohol is not in their blood yet. That alcohol may be getting absorbed into their blood for another hour. By the time the blood is drawn, the blood may have absorbed the alcohol that they drank prior to being pulled over that wasn’t in their system at the time. We can show that the blood test, while maybe it’s over the legal limit, is consistent with the person being under the legal limit at the time of driving, because that’s frequently what happens. People drink some amount, and then get in their car and drive. They get pulled over, get arrested, and that’s quite different from the situation where rather than people drinking and then just sitting around for several hours before they start driving. So that’s another way to cast doubt on whether the person was intoxicated at the time of driving.


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