How Can An Expert Assist In A DUI Case?

The defense of a drunk driving case is often multi faceted with many issues that can be pursued to develop a reasonable doubt.  Most of these issues involve science or the violation of regulatory requirements set forth by the state of California.  In fact, under California law if the government fails to perform the breath or blood test correctly it may rebut the presumption of reliability in the sample.

Most DUI Defense attorneys will tell you that defending a drunk driving case can be complex because of the science involved.  You see, in order to be effective in fighting DWI charges the lawyer must pierce the presumption that the breath test or blood test numbers from the police or lab are indeed accurate and reliable.  Here is how one well known attorney has described it:

"DUI cases can be quite complex when it comes to the chemical test aspects of the defense.  Both breath and blood tests often involve very unique scientific calculations that are difficult for the laymen to understand.  This is where an expert can help. The most common experts used in a drunk driving defense are forensic toxicologists who specialize in the interpretation of an individual’s blood alcohol level at a given point in time.  You see the breath or blood test you took will only tell you the level you are at when the sample was collected.  However, what is important is what the BAC was at the time of driving This is where a toxicologist can assist the attorney.  No one’s blood alcohol level remains constant over time, it changes, either going up or down within a certain period of time.  Importantly, when a person has drank alcohol close in time to the stop, he or she will usually be rising which means their particular BAC  will be lower at the time of driving, this helps the defense. Adjudging what a true blood alcohol level is at a certain time involves complex formulas that take into account absorption rates, burn off rates, and metabolism."

In addition to issues of rising blood, many cases involve situations where a cop or other person does not follow the proper procedures when collecting a blood or breath sample.  For example, the phlebotomist may fail to properly disinfect the puncture site or the collection might violate other state regulations.  Here, as well, an expert can be used to show how the procedures were not followed and explain why the violation affects the integrity and reliability of the sample. Hiring an expert can also be helpful in raising other defences such as contamination of a breath test by mouth alcohol or people that suffer from medical conditions such as GERD.

In some cases an expert in breath and blood testing can establish that the arresting officer failed to follow official standards such as California Code of Regulations Title 17 which dictates how breath and blood samples are to be collected, maintained and tested.  For example, in a breath case the officer may not comply with the mandatory continuous observation period prior to the breath test, codified in Cal Code of Regulations 1219.3.  If the officer does not follow these regulations the attorney can use that both at the DMV and Court to show the breath test results are unreliable.