Why Is A Blood Test Generally Employed In Place Of A Breath Test?
In New Jersey, breath is the required substance to be tested. If a person refuses a breath test, they get punished for it. A person has an absolute right not to submit a blood sample unless the police get a warrant, or they otherwise consent or there are exigent circumstances. There is no such thing as an offense for refusing to provide a blood test. I would recommend to anybody who has to face that situation that you don’t consent to give a blood test. Unless you are absolutely certain that it’s going to show that you are not guilty, you have an absolute constitutional right to maintain the integrity of your body. You also have no obligation to assist the state in prosecuting you except to the extent required by a court, and that’s where the warrant comes in.
If you refuse to give a blood sample after a warrant has been issued, then you can be charged with the criminal offense of obstructing justice. Until that warrant is obtained, or some court order that requires you to submit, you have an absolute right to refuse to give your blood.
How Do You Defend Against Blood Test Results In A DWI Case?
Chain of custody is an important concept, based on relevance. The idea is to make sure that the blood that the cop says he saw leave the defendant’s arm, that blood is the same blood that was tested in the laboratory by the chemist. All chain of custody means is that we properly label the blood sample and we document its movement from one person to the next or from one place to the next. For example, the chain of custody will begin with the nurse or lab technician or doctor drawing the blood. They are the first link in the chain. The next link in the chain would be the police officer to whom they hand the actual tubes containing the blood that they just drew.
The next chain would be a record of that officer placing it into some kind of an evidence refrigerator or vault or handing it to an evidence officer who does that. The next chain would be the documentation about who removed that sample and took it to the laboratory. The next link would be the person who takes it to the laboratory handing it to the clerk that receives that evidence at the laboratory. Even inside the laboratory, it’s tracked when it’s put from that person to an evidence locker or refrigerator. When the chemist removes it, that’s documented. Every link in that chain has to be documented in some fashion, because if there is a break in that chain that would cause us to question the identity of that blood sample as coming from that defendant. A break in the chain of custody can render the sample inadmissible because we don’t know if it’s relevant, and even if it’s enough not to be that serious it can still cause reasonable doubt.
In other words, the reading may come into evidence, but the judge may decide on reflection that there is enough of a question about whether that blood sample was the same one that was taken from the defendant as to cause the judge to disregard it, and possibly find the defendant not guilty. The other areas that you can challenge when dealing with a blood test are whether the sample was properly handled after it was drawn, or whether the site from where the blood was drawn was properly cleaned. We are looking to see if anything contaminated that sample. We look at cleaning the site properly, because if it’s not cleaned properly, there may be contaminants present. If an alcohol swab is used, that can contaminate the sample. If the sample is not properly inverted after it’s drawn, so as to mix the anti-coagulants and preservatives homogeneously throughout that sample, you can get clumping.
In other words, one part of the blood in that vial may have a much different blood alcohol content than blood in that same vial at a different location, only because things weren’t mixed properly and the homogeneity of that sample was not properly maintained. They are only measuring a very small amount of blood from that vial, and so homogeneity is very important. If it’s established, a small amount of that blood can then be extrapolated to compute an appropriate blood alcohol content. So we can attack proper blood draw, proper handling, chain of custody, proper administration of the blood test, and homogeneity of the sample.
How Accurate Is A Blood Test In A DWI Case?
The thing about a blood test compared to a breath test is that it involves a direct measurement of the alcohol in the blood, through either mass spectroscopy or gas chromatography, as opposed to an indirect measurement of the alcohol content of the breath by the fuel cell or electrochemical technology and infrared technology. Again, we are trying to infer blood alcohol content from breath alcohol content, but we’ve already talked about how that can be questioned due to physiological features, contamination features, and administration features. Blood tests are more accurate only because there is less interpretation involved in directly measuring alcohol from the blood, as opposed to inferring it from a different substance.
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