What happens when the prosecutor has evidence that the driver is under the influence of several different drugs or a combination of a drug and alcohol even when any one of those substances would not necessarily be enough to prove impairment? The state will often present testimony about the “synergistic effects” of taking drugs and alcohol on a person’s physical and mental faculties, especially when the blood or breath alcohol concentration (BAC) at the time of testing is at or below .08.

When two or more drugs are taken in combination, the prosecution will often argue that the effects are multiplied or enhanced. Alcohol can also increase the negative side effects of a drug or drugs in the system.

Synergistic Effects Defense Lawyer in Fort Worth, Arlington, Grapevine, Keller, and Southlake, TX

The attorneys at the Law Offices of Richard C. McConathy are experienced in dealing with cases involving allegations of impairment by the combination of alcohol and drugs. Call a Fort Worth DWI attorney to discuss the facts of your case, the penalties that can apply, and the best ways to fight the case for the best possible result.

Call (817) 422-5350 today.

Factors for DWI Impairment by Drugs and Alcohol

In determining whether there is sufficient “other evidence” in the record to support a finding of intoxication, the court will look at a variety of factors including:

  • whether the defendant admitted to consuming alcohol or other intoxicating substances prior to driving;
  • whether the defendant appeared intoxicated at the time of his arrest; and
  • whether the nature of the accident suggested that the defendant was intoxicated.

In Crenshaw v. State, 378 S.W.3d 460, 467-68 (Tex.Crim.App. 2012), the court found that the evidence was sufficient to support a finding of intoxication under an impairment theory where the defendant’s BAC level was 0.07% at the time of blood draw, which together with other evidence of the defendant’s intoxication, including his appearance at the time of his arrest and his admission that he drank and smoked marijuana prior to driving, made it “more probable that Appellant was subjectively impaired at the time he was driving, thereby supporting the theory alleged in the information and applied to the facts in the charging instrument.”

In many of these cases, the prosecutor will ask the court to instruct the jury on the synergistic effects of narcotics and alcohol. Such instructions are deemed a proper application of the law to the facts of the case when the evidence demonstrates the defendant ingested multiple substances prior to driving. See Gray v. State, 152 S.W.3d 125, 128, 133-34 (Tex.Crim.App. 2004).

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DWI with a Combination of Alcohol and Other Drugs

According to the Breath Test Operator Intoxilyzer 5000 Manual, when ethyl alcohol is consumed in combination with other chemical agents, illicit, prescribed, or over-the-counter, the symptoms of alcohol intoxication may be altered. This may explain the situation where an individual appears very intoxicated, but the alcohol test results are low.

Combining ethanol with other drugs can produce two types of effects: additive or synergistic. When one dose of a drug is combined with one dose of ethanol and the effect is equal to no more than the sum of the effects of the two drugs, the effect is said to be addictive.

A synergistic situation occurs when a drug is combined with ethanol and the end result is greater than the sum of the individual effects. There is no known drug that can lessen the effects of ethanol on a person’s driving performance.

Texas Resources for DWI Arrests

Find a DWI Lawyer in Dallas, TX – Visit the Lawyer Legion website to find a list of the best DWI attorneys in Dallas, TX. The ranking system used by Lawyer Legion provides information about an attorney’s membership and leadership in the top bar associations for DUI defense and criminal defense including the National College for DUI Defense (NCDD), the DUI Defense Lawyer Association (DUIDLA), the National Association for Criminal Defense Lawyers (NACDL), and the Texas Criminal Defense Lawyers Association (TCDLA).

Texas Department of Public Safety on DWI Law – The Texas Department of Public Safety (DPS) is a law enforcement agency that seeks to protect and serve Texas by combating terrorism and crime, enhancing public safety, and strengthening emergency management throughout the state. A local Dallas DPS office is located at:

1500 Marilla 1B South
City of Dallas Building
Dallas, Texas 75201
Phone: (214) 651-1859

Dallas County Clerk’s Office – This link provides individuals access to their criminal records and misdemeanor criminal case information, miscellaneous court information, and resources about the justice system throughout Dallas County. The county criminal courts are located at:

Frank Crowley Criminal Building

133 N. Riverfront Blvd.
Dallas, Texas 75207
Phone: (214) 653-7099

Find A Tarrant County Defense Attorney for DWI / DUI | Law Offices of Richard C. McConathy

If you have been arrested for drinking and driving, it is important that you contact an experienced DWI/ DUI attorney immediately. Richard C. McConathy focuses on drinking and driving cases and is an experienced criminal defense attorney in Dallas Fort Worth.

Law Offices of Richard C. McConathy serves those accused of drinking and driving throughout Tarrant County, Southlake, Fort Worth, Arlington, Grapevine, and Keller, TX area. Contact the Law Offices of Richard C. McConathy as soon as you possibly can.

Email or call (817) 422-5350 today to get a consultation.

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