Top 4 Chemical Test Defenses

For Drug & Alcohol Related Hearings

Top 4 Chemical Test Defenses

For drug and alcohol-related hearings, a chemical test report is often the main evidence against a motorist. Most of these defenses challenge the use of the report in the first place because the rules for using hearsay evidence were not satisfied. (A chemical test report is considered hearsay evidence and must satisfy certain exception rules to be used by DMV.)

The rising blood alcohol defense, on the other hand, does not challenge the use of the report. Instead, it argues that motorist had a legal blood alcohol concentration (BAC) at the time of driving but continued to rise until, at the time of the test, it had risen to .08% or greater.

These defenses take some skill and may require an expert to testify. But they can be the most powerful weapons in the motorist’s arsenal because DMV will not have an expert to rebut them.

Chemical Test Defense #1

RISING BLOOD ALCOHOL

This defense is the most common chemical test defense in low blood alcohol concentration (BAC) cases. It is based on the premise that it is only illegal to have a prohibited BAC at the time of driving; it is not illegal to have a prohibited BAC later at the time the test is done.

This defense requires expert testimony from a biologist, medical person or toxicologist.  Neither a motorist or a lawyer can provide this testimony themselves.

Chemical Test Defense #2

TEST MORE THAN 3 HOURS AFTER DRIVING

In all alcohol-related administrative hearings, DMV must prove the motorist had a prohibited BAC at the time of driving. So long as the breath or blood test was done within 3 hours of the time of driving, the Vehicle Code allows DMV to presume (pretend, really) that the reported BAC was the BAC at the time of driving.

If the test was performed more than 3 hours after driving, it is very difficult for DMV to establish the BAC at the time of driving. Such a showing requires an expert witness who will perform retrograde extrapolation–a fancy term for “making it up” with math.

Chemical Test Defense #3

TEST VIOLATED TITLE 17 REQUIREMENTS

This defense relates back to Procedural Hearing Defense #4: Use of Hearsay as Sole Evidence. A breath test or blood test report is hearsay and requires DMV to show that an exception applies to use it as the sole evidence of BAC at a hearing. One part of that showing is that the test be reliable. 

Title 17 is the set of regulations that govern alcohol testing in California. If a motorist can show that Title 17 was violated, then the test is no longer reliable and the hearsay exception does not apply.

Chemical Test Defense #4

NO “OFFICIAL DUTY” FOR TESTER

This defense relates back to Defense #3 above.  A breath test or blood test report is hearsay and for DMV to use it as the sole evidence of BAC at a hearing, it must show that the person performing the test had an official duty to perform the test according to established procedures.

This defense applies more often than you might think. For example, if the person signing a blood test report does not use the Title 17 job title for their signature, there is no “official duty” and no hearsay exception. If Title 17 does not spell out the actual duty (as in the case of a preliminary alcohol screening (PAS) test), there is no “official duty” and no hearsay exception.

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