Attorney at Law

Chemical Test

James Parker
February 16, 2022
Last reviewed by
August 17, 2023

What Is a Chemical Test?

A chemical test is, in the broadest terms, a test administered using chemicals for the purposes of determining a subject’s blood alcohol content (BAC). These tests will typically examine either the user’s breath, blood, saliva, or urine in order to calculate the individual’s BAC at the time of submission. Each of these forms of chemical tests have their own benefits and drawbacks as well as their own sources of error.

A breath test has the advantage of being the most convenient to collect. A breath sample can usually be analyzed with a breathalyzer which is a portable device that most individuals can easily use. There are, however, some errors with breath analysis. To begin with, a breath analysis cannot give a perfectly accurate measure of blood alcohol levels. Less than 10% of alcohol in the blood is evaporated in the lungs and exhaled on the breath. This makes breath analysis inherently less accurate.

The other drawbacks are contamination and frequency. Because the mouth is not only used for breathing, there can be other substances that interfere with the breathalyzer’s measurements. The device itself can also be miscalibrated or react with environmental stimuli. Beyond that issue, a breath test must ideally be taken several times at intervals a few minutes apart in order to confirm the accuracy of the results. This can impair the convenience of their use.

Blood tests are the most accurate form of chemical test. For this method, blood is drawn by a phlebotomist and sent for laboratory analysis where it is examined and the results are returned. Blood tests are highly accurate and precise but there are, however, several drawbacks to this method. 

To begin with, a blood test requires several specialists and at least one specialized facility to ensure accuracy. This can mean that if expedience is key, blood tests can be too slow. Additionally, while blood tests are very accurate, they are not immune to contamination that can occur from improper sterilization techniques or even just mixing up samples at the facility. 

Urine tests are a middle ground between breath and blood tests that unfortunately inherit many of the problems associated with both. First, while they are convenient, urine tests are based on alcohol metabolized through the kidneys and, like breathalyzers, measures an approximation of blood alcohol levels rather than measuring the blood itself. Additionally, urine tests are not very quick and therefore cannot return results as quickly as other methods. 

Key Takeaways

  • Chemical tests are a key way that BAC is measured in criminal and civilian procedures.
  • Not all chemical tests are the most valid or rapid in court procedures.
  • Refusing to take a chemical test can have dire consequences, including suspension of the driver’s license.
  • If you have been charged with a DUI on the basis of a chemical test, an experienced DUI attorney may be able to improve the outcome of your case by leveraging experience and expert testimony.

Chemical Tests and Driving Under the Influence (DUI) Charges 

Chemical tests are a key component of DUI charges. A suspect may have to submit to a breathalyzer test during a roadside stop, they may be asked to submit to a blood or urine test, and they may have their saliva swabbed to confirm BAC measurements. Citizens may then be wondering, is it mandatory to submit to these chemical tests or is this a form of self-incrimination?

The fifth amendment of the United States constitution protects citizens from incriminating themselves or being compelled to incriminate themselves. However, this is not applicable to chemical tests. One of the points in the fine print of a driver’s license is an agreement by the driver to submit to any chemical testing that may be required by legal or government officials. This clause is known as the implied consent clause.

This means that although a citizen has the right to revoke their consent, in most states it will be accompanied by an immediate suspension or even revocation of their driver’s license. Additionally, if the police are able to obtain a warrant from a judge, a blood sample may be taken from an individual without that individual’s consent. That means that even if someone refuses to take a chemical test, potentially sacrificing their driving privileges, they may simply be forestalling the inevitable. 

There are also additional conditions that will be applied to individuals who refuse to comply with a chemical test. They may have to apply for a temporary restricted license, which limits when, where and how an individual may operate a vehicle. The individual may be charged with unlawful refusal, along with suffering any associated fines or jail time. Finally, while refusing to submit to a chemical test may prevent that BAC reading from being entered as evidence, the individual’s refusal to submit to a chemical test can be used as evidence against them in their DUI trial.

Individuals choosing to pursue this course of action should consult an attorney immediately.

Bottom Line

A DUI charge is often filed on the strength of a chemical test. Chemical tests can be the breathalyzer test that substantiates an arrest, or the evidence that supports it. If you have been charged with a DUI, you will need an experienced DUI attorney to help fight for you.

A DUI attorney can challenge chemical test results, cross-examine the arresting officer, argue for the reversal of a license suspension, and advocate for the best possible outcome for your case.

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