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Is It Mandatory For Someone To Perform The Field Sobriety Tests?


In California if you are older than 21 you do not have to do the portable breath test before a DUI arrest. Not only do you have the right to refuse but the police officer is required by law to tell you that you have the right to refuse. Of course if you are under 21 then that’s a different story. If you are also asked to do field sobriety tests those are completely voluntary at all times. The field sobriety tests that I’m talking about are finger to nose, walk the line, stand at attention, I’m using common terms for these types of field sobriety tests but they are completely voluntary and our clients performing the field sobriety test oftentimes actually helps us win their DUI cases in court.

Sometimes, if you are on DUI probation, you have to submit to a portable breath test and again if you are under 21 its zero tolerance but if you are older than 21 it’s actually 0.08 or greater.

How Accurate Are These Tests In Determining Alcohol Impairment?

Let’s first talk about breath testing both pre-arrest and post-arrest. The pre arrest breath tests are administered when the person is still being investigated. A lot of times on the street they will give another evidentiary post arrest breath test on the same machine or on the same type of machine, the portable handheld breath test machines. Also after somebody is arrested for a DUI they are taken back to jail and administered breath tests on big desktop machines but I’m going to characterize both of these breath testing machines as breath testing in general. In my professional opinion breath testing is not accurate at all to determine the alcohol level in a person’s blood.

The first and obvious reason is that the breath test machines are measuring alcohol on a person’s breath not alcohol in a person’s blood. All breath testing machines in California are calibrated to assume that the relationship between the alcohol on the person’s breath and alcohol in their blood is the same. The ratio for breath and blood is always the same for all people at all times. That is called the partition ratio but the ratio is set by statute and the legislature that incorporated this ratio into the statute was based on merely an average; not for all people at all times.

So let’s say a person is 6’5 and 300 pounds, all breath testing machines assume that the ratio between alcohol on that person’s breath and that person’s blood is the same as a 115 pound female and it’s just not the case. To further prove my point that breath testing more often than not gives two different results within minutes apart. For example a person can end up with a 0.16 and then a 0.18, 2 or 5 minutes apart. It is scientifically impossible for a person to go from a 0.16 to 0.18 in a span of 2 to 5 minutes. In California breath test consists of two separate breath samples. It is the same in reverse. If a person has a 0.20 breath test and shortly after that, 2 to 5 minutes later has a 0.18 breath test then that’s scientifically impossible for a person to go from a 0.20 to a 0.18. The same is true of 0.08 and a 0.11 and a 0.09. It’s just not accurate.

There are many other scientific reasons why breath testing is not accurate but just more often than not the results themselves call into question the breath test results that were administered. Adding on to that, if a person has 2 breath test results on the street and the after being arrested, they have another breath test result which is another half an hour or 45 minutes later or a blood result a half an hour or 45 minutes later or even an hour and half or two hours later, the numbers oftentimes are inconsistent where the person is comparing it between when a person is being investigated versus where a person is being tested after the arrest and so there are many scientific reasons for these. The command of a large body of scientific knowledge in order for a good DUI defense attorney to be able to fight and win DUI cases both alcohol and drugs. There are different issues as it relates to DUI drugs.

For example the amount of nanograms in a person’s system can somehow indicate that a person may not be under the influence of drugs. At the present time, there is no statutory level of the amount of drugs in a person’s system to assume that the person is in fact impaired and driving under the influence like there is with alcohol for 0.08 or greater.

For more information on Field Sobriety Tests In A DUI Case, a free initial consultation is your next best step. Get the information and legal answers you are seeking by calling (888) 486-7486 today.

Top Gun DUI Defense Attorney Myles L. Berman

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