How do prosecutors build DUI cases, and why is experienced defense advocacy necessary?

On Behalf of | May 9, 2017 | Criminal Defense

Most people understand that it is important to work with an experienced criminal defense attorney when facing drunken driving charges, if for no other reason than they do not understand the legal process and how to build a strong defense case. While in every drunken driving case, the goal is to resolve the matter to the best benefit of the defendant, each case is different, and different strategies are used depending on the facts of the case.

As in other states, there are two general ways an individual may be charged with drunken driving in Pennsylvania. One possibility is for a driver to be charged based on the level of intoxication. By statute, those found to be driving, operating or in actual physical control of the movement of a vehicle with a blood or breath alcohol concentration of between 0.08 and 0.10 percent within two hours of driving may be charged with driving under the influence. These cases are also known as DUI “per se.” 

In DUI per se cases, the reliability of the breath or blood test is a critical issue, and there are a number of factors that can possibly throw off the reliability of tests. One potential issue is that the software that makes breath testing devices functional needs to be properly designed, tested, and approved by the appropriate scientific community. If any changes have been made to the software after its approval for use in law enforcement, those changes also need to be subjected to scrutiny.

Another potential issue with breath testing is that the device must be properly calibrated and used correctly, by an individual with training in how to use the device. Breath testing devices must also be properly maintained to ensure they are in working order.

With blood testing, reliability is also important to scrutinize, and this includes looking at whether the blood test was properly performed by an individual trained and approved to take a blood sample for DUI investigation purposes. The chain of custody for the blood sample also needs to be scrutinized to ensure there was no tampering or other issues that could call into question the accuracy of the results. Rate of error should also be considered in scrutinizing blood alcohol test results.

In our next post, we’ll continue looking at this issue, and the importance of working with an experienced attorney in building a strong DUI defense case. 


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