Currently, approximately 1.5 million people in the USA are charged with driving under the influence (DUI) every year. The base definition of DUI is the crime of driving a vehicle while under the effects of an intoxicating drug, such as alcohol or drug use. As far as alcohol is concerned, those under the age of 21 can have a blood alcohol concentration limit of anywhere from 0.00 to 0.002 depending on the state, while for those over the age of 21, the limit is typically 0.08. (http://www.drinkingandyou.com/site/us/drive.htm)
The penalties for DUI are extremely serious as drunk driving causes thousands of dollars in damages, not to mention many wrongful deaths every year. The penalties range from fines to a loss of driving privileges, to a combination of the two.
These tests are administered via breathalyzer, which is then admitted into court as evidence. People are usually charged with DUI after a roadside stop or at a sobriety checkpoint under which they are suspected to be under the influence. From there, the matter is left to the courts. Once in court, two things must be proven beyond a reasonable doubt:
● The person being charged was driving a vehicle.
● They were doing so under the influence, i.e., impaired by drugs or alcohol.
Both of these conditions must be proven to secure a conviction.
Therefore, most of the defenses center on disproving one or both of these prerequisites.
Definition of “Driving”
Depending on the state, it has to be proven that the person was actually actively driving, and in motion at the time of the stop. Those who were simply sleeping in their car while intoxicated aren't likely to be convicted of drunk driving since they weren't actually driving during the time of the alleged offense. Other states are less forgiving, however. Some states define being "in physical control" or "operating" the vehicle, as being in the car in any capacity, while intoxication can be enough to be charged in some jurisdictions.
Defenses Related to Arrest
There are procedures relating to how an individual was arrested that can be used to make a defense against DUI. At times, poor adherence to proper arresting procedures can get a case thrown out of court. Some of these include but aren't limited to:
Lack of Probable Cause
For your vehicle to have been stopped in the first place and a breathalyzer administered, the arresting officer needs probable cause. The only exception to this rule is that DUI checkpoints are exempt from requiring probable cause, as their primary purpose is to detect drunk drivers. For stopping your vehicle, any traffic violation is enough to have you stopped. From there, the officer requires an adequate reason to have believed you to be in violation of the DUI laws of the jurisdiction in question to have administered a breathalyzer test. This reason is typically related to either behavioral cues like slurring of speech or a detectable odor of alcohol on the breath of the person charged. Failing a field sobriety test is also considered as proper probable cause to be administered a breathalyzer test.
If the officer had no reason to stop you in the first place, then all subsequent evidences would typically be inadmissible in court. If the officer didn't have adequate reason to administer a breathalyzer test, then the DUI charge would typically be thrown out as the evidence derived from the breathalyzer test was gained illegally.
Failure to Read Miranda Rights
It should be noted that Miranda only deals with a suspect being questioned. Before any suspect is questioned by the police once in custody, they need to have been read their Miranda rights. If a suspect makes incriminating statements while in custody that then leads to a breathalyzer test and a subsequent DUI charge, the charges may be thrown out if the person in custody wasn't read their Miranda warnings before being questioned.
Improper Administration of Breathalyzer Test
Specific rules are surrounding how breathalyzer tests are to be administered. First off, the tube to be blown into must be fresh and uncontaminated, and the machine should be recently calibrated and properly maintained. If the defendant can call into question those two issues or that the test wasn't properly administered, there's a chance that the case can be thrown out of court.
Challenging the Accuracy of the Test
The scientific principles behind a breathalyzer test can be changed by certain factors, which can result in false positives as well as false negatives. To prove these points, typically expert witnesses, who can explain these scientific principles to the court and why the defendant was erroneously thought to have blown over the legal limit, will have to be called in.
Firstly, some foods and medications can cause a false positive on a breathalyzer test if they have been ingested soon before the test was administered.
It should be noted that testing during the absorption phase also complicates things when it comes to securing a DUI conviction. It takes anywhere from one to three hours for alcohol to become absorbed into the body. This means that alcohol can be consumed directly before driving a vehicle, and that while driving, you may not be legally impaired. However, if you're pulled over and sit for a significant period of time before being administered the test, you may then be over the legal limit. The defense here hinges on the fact that you weren't actively driving impaired, but you were proven to be impaired solely due to the fact that you were stopped and were given time for the alcohol to absorb into your bloodstream.
Any of these defenses will require the expertise of a lawyer because not every case is the same, and the specifics need to be considered before the strongest defense is to be decided. A lawyer who specializes in DUI should be sought out, as there are a lot of specifics that complicate these cases. With the right lawyer, mounting a successful defense is much more likely.