DUI Lawyer Chicago Heights Illinois | Reliability of Different Blood Alcohol Tests

When a vehicle is pulled over by a law enforcement officer due to a traffic violation, they might observe indications of the driver being intoxicated by alcohol. If they find cause to arrest you and you need an attorney, contact our DUI lawyer Chicago Heights Illinois at The MacNeil Firm for a consultation. Call 815-290-9170 or 708-919-5415 today to hire attorneys with experience and a commitment to winning. 

If the officer becomes suspicious and believes the driver could be a potential DUI suspect, they will likely request the driver to perform a field sobriety test. This marks the initial step in a series of potential assessments employed by law enforcement to establish grounds for the arrest and charges related to driving under the influence. There are additional steps and tests they administer to bolster their case, but the reliability of those tests can vary. 


The preliminary breathalyzer test (PBT) that is used by police officers in the field is the most common and widely used blood alcohol test. It’s also the least accurate. It’s a breath analysis device that measures the amount of alcohol in your breath, and it’s not as accurate as other tests. Because you can breathe out all you want when using this method, there are ways to trick it into getting lower readings than what they actually are. 

Another issue with preliminary breathalyzers is that they don’t take into account how much food has been consumed during an individual’s day, a factor which affects how quickly someone gets drunk after drinking alcohol. 

Because there can be flaws with the reading, how the test is administered, and the device itself, the PBT cannot be used in court. The results of this test are not evidence of your BAC but are merely a tool to help the police determine whether to arrest you for DUI.

If you have consented to a PBT and believe the test was flawed in some manner, a DUI lawyer Chicago Height Illinois can help. The dedicated and passionate attorneys will be able to evaluate your case and test results and determine your best course of action. 

Blood Test

A blood test is the most accurate test, but it’s also the most invasive and it can only be used if you have been arrested for driving under the influence (DUI). A medical professional will take a sample of your blood so they can measure its alcohol content. A blood test can also detect whether you’ve been drinking over a long period of time.

Blood is tested at a lab using a process called gas chromatography and the results are analyzed and a report is sent back to the police department for use in your trial. These procedures add a number of changes in custody for your blood sample and can often be an area an experienced defense attorney can challenge. 

Because they are more reliable, they can be used in court. However, an experienced DUI lawyer Chicago Heights Illinois, can challenge the results in a variety of ways. If the test was not done by a qualified professional, if it wasn’t stored properly, if there was faulty equipment used, or if the chain of custody was broken, these things can be challenged in court. 

Urine Test

A urine test is more accurate than breath tests. A urine test can detect BAC as low as 0.01%, which means that even someone who has only had one drink can be detected by a urine test. This level of accuracy is not possible with breath testing devices or blood tests because they cannot detect such small amounts of alcohol in the body. 

Urine tests can detect BAC for several days after drinking, even if you haven’t had any alcohol recently at all. In fact, studies have shown that some people will still register positive results on their urinalysis after abstaining from alcohol for up to five days before taking their sample. This makes urine tests less reliable than other methods because there’s no way of knowing exactly how much time has passed since your last drink and, therefore, no way of knowing whether or not your results are accurate enough to constitute proof beyond reasonable doubt in court situations where this standard applies.

The urine test is also less reliable than either of these two tests because some people don’t absorb alcohol into their bloodstreams quickly enough to get an accurate result; this means they may pass a urine test while still being over the legal limit.

A urine test may be used in court in Illinois. However, because there are several issues with this type of testing, a strong DUI lawyer Chicago Heights Illinois should be able to help you fight it. Contact the MacNeil Firm today for an evaluation of your case. 

Contact a DUI Lawyer Chicago Heights Illinois to evaluate your case

It’s important to know what type of test you are given and the potential issues with those tests. Nothing is 100% reliable and that means there is potential to challenge the results in court. The DUI lawyer Chicago Heights Illinois at the MacNeil Firm are here to help. Contact us today.