Defense Expert Testimony on Reliability of Intoxilyzer Allowed in New Mexico

The New Mexico Court of Appeals case of State v. King concerns the use of expert testimony in New Mexico DWI cases.

The Court had to determine whether a defendant should be permitted to present expert scientific testimony related to the general reliability and accuracy of the Intoxilyzer 8000 machine which is used to determine his breath alcohol content.

The Court allowed the expert testimony holding that testimony generally on the Intoxilyzer 8000 would apply to all such machines. The Court refused the assertion that the expert testimony should be excluded because the expert did not examine the specific machine used in the case.

The facts of the case are pretty straightforward. The defendant was arrested for a DWI. A police officer stopped the defendant for a possible seat belt violation and observed signs of intoxication.

The officer read the defendant the Implied Consent Act and performed a breath alcohol test on the defendant using an Intoxilyzer 8000 machine. However, the officer was not a “key operator” of the machine and didn‘t know how it worked. A “key operator” is someone that the SLD assigns to make sure that the machine is working properly. The machine registered the defendant‘s alcohol concentration as above the legal limit.

At trial, the officer testified that he knew the Intoxilyzer 8000 was working properly because the machine‘s calibration log showed that the machine had passed its diagnostic tests. The defendant wanted to call an expert witness who would testify about the reliability and accuracy of the machine.

The proposed witness was an expert in pharmacology and toxicology with an analytic chemistry background. The expert had also been trained to use the Intoxilyzer 8000. The defendant indicated that the expert witness would testify about the “possibility of inaccuracies, including inaccurately high readings” in the machine.

The witness wouldn‘t be testifying about the specific machine used to test the defendant‘s blood alcohol concentration, but rather about the general workings of the Intoxilyzer 8000.

The district court didn‘t allow the defendant‘s expert witness to testify for three reasons. It indicated that the expert couldn‘t testify to the validity of the specific machine used in the defendant‘s case, that the testimony wasn‘t relevant since state law authorized the use of these machines, and that the testimony either wouldn‘t be probative or would have a high prejudicial effect that would outweigh its probative value. The defendant was convicted and appealed to the New Mexico Court of Appeals.

The Court of Appeals first looked to state law on expert witness testimony, which says that an expert witness can testify in the form of an opinion if “scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue.”

The Court then looked to the defendant‘s purpose in proposing the expert testimony. Depending on the defendant‘s purpose, the Court could determine whether the testimony was permissible.

The Court explained that the purpose of the expert witness‘s testimony would be to challenge the reliability of the breath alcohol test that the officer performed on the defendant in order to raise reasonable doubt that his alcohol concentration was above the legal limit. Would the expert witness‘s testimony contesting the reliability of the Intoxilyzer assist the trier of fact?

The Court looked to previous case law. In State v. Martinez, the New Mexico Supreme Court said a defendant “may successfully challenge the reliability of the breath test” in a DWI case. The Court reasoned that the district court‘s failure to admit the expert witness testimony limited the defendant‘s ability to challenge the reliability of the Intoxilyzer. Even though the witness would only have testified to the general unreliability of this type of machine, that testimony would have been “relevant to the reliability of the Intoxilyzer 8000 used to test the defendant.”

The State argued that the Implied Consent Act prevented a defendant from challenging the reliability of an Intoxilyzer test. However, the Court made clear that even when a machine is approved by the SLD and operated and maintained in accordance with SLD standards, those facts alone don‘t automatically mean that the test results are “conclusively reliable.” As a result, the Court reasoned that a defendant can argue that a machine like the Intoxilyzer didn‘t provide reliable results.

The Court concluded that the district court erred when it said the expert witness‘s testimony wasn‘t relevant since “any reliability ‘pitfalls‘ based on the ‘structure, mechanisms, and workings‘ that are common to the Intoxilyzer 8000 machines necessarily could impugn the reliability of every Intoxilyzer 8000 machine, including the Intoxilyzer 8000 used on the defendant.” It did not matter that the expert did not examine the specific machine in question.

Further, the Court disagreed that unfair prejudice to the State would outweigh the probative value of the expert witness‘s testimony, as a jury is unlikely to be “confused or misled by the only method for the defendant to challenge the scientific aspects of the Intoxilyzer 8000.” As a result, the Court found in favor of the defendant and reversed the district court‘s holding.


Related Reading:
Standardized Field Sobriety Tests Serve as Surrogate to Chemical Testing in New Mexico DWI
New Mexico‘s Impaired to the Slightest Degree DWI Standard Has to Go!
Refusal of Breath Alcohol Test Carries Big Risks and Little Reward in New Mexico DWI Cases

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