What is a Chemical Test

What is a Chemical Test

During an under-the-influence traffic stop initiated by law enforcement for observing suspicious driving patterns, you will probably be asked to take a breath test. This is supposed to determine your BAC or blood alcohol content by measuring the amount of alcohol in your breath. 

This may be called a preliminary alcohol screen. 

You can legally refuse to take a breath test without consequences as long as it’s prior to any arrest. After your arrest, you fall under implied consent laws in all 50 states. This law requires you to submit to chemical testing upon request by law enforcement after an arrest for DUI.  

You cannot refuse a chemical test without risking harsh penalties against your license. 

In most states, the legal BAC limit for a driver is .08 percent. Commercial drivers may be required to have a lower BAC, typically less than .04 percent.

Legal Limits and Arrest for DUI

DUI stands for driving under the influence. This isn’t necessarily due to alcohol. It could also be for drugs and/or a combination of the above. This could be for medications legally prescribed to you and even for drugs available over the counter. 

Certain antihistamines are particularly germane. Some types can even cause profound drowsiness.

What Are Urine Tests and Chemical Tests?

Both law enforcement and medical professionals use chemical tests to check for evidence of certain drugs, including alcohol, from your blood sample. In general, drug and alcohol tests work by looking for compounds called metabolites within the provided blood sample. Some chemical tests are only qualitative; other blood tests are both qualitative and quantitative. 

Metabolites are by-products produced by the body as it breaks down or metabolizes a drug. Some drugs have many known metabolites that they may share with other drugs. However, chemical tests look for known metabolites unique to that particular drug. 

The metabolites of some drugs must be interpreted correctly by a trained medical lab professional to give accurate results for the chemical test. For example, heroin, codeine, and morphine all share the active metabolite morphine. Determining which one the subject actually took and the amount requires a trained lab professional to analyze the chemical test.  

A qualitative chemical test only reports if specific chemical substances are present or not. A quantitative chemical test reports how much of the substance is present in the blood, breath, or urine. From these chemical tests, it’s possible to accurately determine how much the person ingested from the blood sample. 

In the case of alcohol and chemical testing, this is represented by the BAC or blood alcohol content. Alcohol is unusual in that it’s partially absorbed directly into the stomach and reaches the bloodstream in a matter of minutes. Most drugs ingested orally must go through the liver before reaching the bloodstream and target organs. 

Alcohol and Acetaldehyde Within a Blood Test

Acetaldehyde is alcohol’s main known metabolite and is dedicated during chemical testing. If this compound is present in the blood sample, the person ingested alcohol within the last 6 to 12 hours. Chemical tests like urine tests, although rarely used, will reveal detectable levels of alcohol for about two to three days after the last drink. 

A preliminary breath test will reflect BAC for about 12 to 24 hours, but these tests don’t provide reliable results like a blood or urine test. 

Implied Consent for a Breath or Blood Test: Know Your Rights

If stopped by law enforcement for suspicion of drunk driving, it’s important to understand the significance of implied consent laws. This law states that as a condition of being granted the privilege of a driver’s license, you agree to the testing of your blood, urine, or breath by a law enforcement officer if they suspect you of drunk driving. 

You cannot refuse a breath or blood test without facing very harsh consequences against your license later.

However, implied consent only applies after your arrest for drunk driving, not before. You do not have to comply with law enforcement’s request for breath tests or chemical tests before that time. 

Understanding More About the Breath Test

It’s important to also understand the limitations of breath tests and their ability to detect alcohol. False positives are possible from taking certain medications.   

Many liquid medications contain alcohol. On labels, drinking alcohol may be listed as ethanol. If you recently took medication with ethanol, it could trigger a false positive on a breath analysis test.

Even if you’ve been drinking, you don’t have to submit to a road breath analysis and test. In most cases, if you’re arrested, you will later be offered a choice between a blood or breath test. At this point, you cannot refuse these breath and blood tests without putting your driver’s license at serious risk. 

Law enforcement can also get a warrant forcing you to submit to blood tests or chemical tests at a legally certified police lab or approved hospital. 

DUI Traffic Stop Procedures for Breath Tests

If you decide to comply with a request for roadside breath tests, know the following:

In all states, law enforcement officers must follow a strict procedure to administer this type of testing:

  • Correct timing of the sample
  • Proper sample observation and analysis of the test subject
  • Ensuring correct machine calibration for the tests
  • Proper and complete instructions to you before any tests
  • Cleaning and maintenance of the machine to avoid contamination and any outside influence

Any mistake by law enforcement during the testing will likely invalidate the test and its evidence. 

A blood test cannot be done during a traffic stop. You will be transported to a hospital or certified police lab for testing of a urine or blood sample to be used as evidence. 

Legal Representation for a DUI and Chemical Testing Evidence

If you’re arrested for DUI, called DWI in some states, and asked to do a blood or urine test, you should seek an experienced DUI lawyer immediately. Consequences for even a first offense are serious and costly, so it’s important to understand your rights regarding blood tests and combination tests. 

A competent attorney with experience in DUI defenses may be able to reduce your license suspension time or even partially eliminate it, fight for a plea bargain with reduced penalties, and challenge chemical test procedures and sample results.