Should You Take a Breath or a Blood Test?

Posted by Jon Ibanez on November 16th, 2015

One of the biggest areas of confusion when it comes to a California DUI is the chemical test. More specifically, one of the most asked questions regarding the chemical test is whether a person should submit to a breath or a blood test.

Before I get into whether a breath test or a blood test is better, let me start off by saying that, yes, California law requires that someone who has been arrested for a California DUI submit to a chemical test. Any test requested by an officer prior to arrest, including field sobriety tests and a pre-arrest breathalyzer (called a “PAS” test), is optional. And I would never suggest submitting to them. Why give the officers any more reason to arrest you when you don’t have to?

Once a person is lawfully arrested for a California DUI, however, they must submit to a chemical test under California’s “Implied Consent” law which can either be a breath or a blood test.

Ok, so now on to the question of whether a person should submit to a breath test or a blood test after they’ve been lawfully arrested. Unfortunately, like many questions dealing with the law, the answer is: it depends.

The blood test is far more accurate than the breath test and much less likely than a breathalyzer to produce a false reading. Also, when law enforcement draws blood from a DUI suspect, they are required by law to preserve a sample of the blood for the defense. This means that the defense attorney can request that a portion of the blood be sent to an independent analyst for re-testing. This is called a “blood split” and is used to contradict the results of the state blood test results or possibly to show contamination of the blood sample.

If a person knows that they are under the legal limit and a blood test is likely to show that they are under the legal limit, a blood test might be the better option because it is more accurate. On the other hand, for the same reason, the blood test may not be the best option for someone who will likely test over the legal limit.

The breath test is far less reliable than the blood test and can be inaccurate for a number of reasons. Without addressing all of the problems with breathalyzers here, I’ll just point you to Lawrence Taylor’s post:

http://ltduiblog.wpengine.com/2014/09/09/are-breathalyzers-accurate/

In fact, it is not uncommon for a breathalyzer to provide a false positive result for someone who is actually under the legal limit.

While the general accuracy of breathalyzers cannot be legally challenged as a whole, a skilled California DUI defense attorney can challenge the reliability of the particular breathalyzer that was used in a DUI arrest.

If a person knows that they are likely to be above a 0.08 percent blood alcohol content, the breathalyzer is likely the better option because it is easier to refute the results.

So to answer the question of whether a breath or a blood test is the better chemical test, it really does depend. It depends on whether the person believes they are actually over or under the legal limit. If you believe that you are under the legal limit, the blood test is the better option because the accuracy of the blood test will show that you are, in fact, under the legal limit. On the other hand, if you believe that you are over the legal limit, the breath test is the better option because it is easier to refute the results.

 

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