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An expert witness is someone who knows more about a subject than the average person. For instance, an expert witness could be someone like a toxicologist, chemist, or someone with expertise in DNA analysis. However, not every expert requires Ph.D. level schooling. A mechanic who runs their own shop could be considered an expert in auto repairs. In some cases, the two parties disagree about who should be considered an expert and request a hearing. The judge then decides if the person can testify in trial and the scope of their testimony.

Expert witnesses in Dallas DWI cases are sometimes used to testify about breath or blood test results. In some situations, police officers themselves may be deemed experts in field sobriety testing. For help challenging the prosecution’s expert or seeking expert testimony for your defense, contact an experienced DWI attorney.

Expert Witnesses in DWI Prosecution and Defense

When prosecuting a DWI case, the state will often call upon the police officer, the person who analyzes the blood specimen for alcohol or drugs, or the person who maintains the breath test equipment and is trained in how breath testing works. If the person is suspected of being intoxicated on a substance other than alcohol, the prosecution may call a police officer with special training in drug recognition as an expert witness.

The defense may also call expert witnesses in Dallas DWI cases to challenge certain aspects of the evidence. For example, a defense attorney may hire someone who is an expert in field sobriety testing to challenge the administration of the tests. They may also hire a toxicologist to testify about the protocols and procedures used to generate the breath or blood test results. An expert can examine the state expert’s testimony and explain why they agree or disagree with it.

Challenging Expert Testimony

In many Dallas DWI cases, there is controversy over whether certain expert testimony should be allowed. For example, the prosecution may call an officer to testify about field sobriety testing, but questioning by the defense attorney may reveal that the officer is not as familiar with testing as they should be. If they make a lot of errors, the defense may be able to challenge what they can actually testify to. Another common example concerns experts in laboratory blood testing. The expert witness may have the training needed to talk about testing procedures, but that does not mean they can testify about how drugs affect the human body.

In these situations, a DWI defense attorney can challenge and potentially limit the scope of the expert’s testimony. The defense is entitled to have a hearing away from the jury where the judge will listen to challenges and make a decision whether or not the testimony will be allowed. The judge may rule that all of the testimony is allowed, part of it, or none of it. This is called the gatekeeping function.

Benefits of an Experienced DWI Attorney

There are benefits to hiring an attorney who knows reputable experts. Hiring an expert witness does not guarantee that someone will win the case, but it can be helpful. Someone accused of driving while intoxicated should seek out an attorney who has the background needed to understand how to use an expert effectively, what issues to focus on in the trial, and what questions to ask.

If you were charged with a DWI in Dallas, you want an attorney who has extensive knowledge of DWI law and experience handling similar cases. For instance, an attorney who has been trained in field sobriety tests is better equipped to question an expert in field sobriety tests. While expert witnesses in Dallas DWI cases can be helpful, it is important to seek out a lawyer who knows how to use them effectively and ask the right questions.

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