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Scientific Evidence

Sep 10
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Court Rejects Blood Alcohol Content Evidence by Unqualified Expert in DWI Case

By DWI

Rejecting the “Science” of Retrograde Extrapolation in Texas DWI Cases

Most people are familiar with the blood alcohol concentration (BAC) level for DWI: 0.08.  Most people, however, are not familiar with “retrograde extrapolation” and the role it plays in determining BAC. A Fort Worth Criminal Defense Attorney will understand the importance of retrograde extrapolation in a DWI case as evidenced by a recent decision from the Texas Fourteenth Court of Appeals.

VELIZ v. STATE (14th Court of Appeals, Houston, 2015)

FACTS: Houston Police Officer Joel Quezada arrested Luis Veliz shortly after midnight. Veliz admitted to having two beers to drink. After Officer Quezada obtained a search warrant, Veliz’s blood was drawn at 3:32 a.m. Veliz’s BAC was .081.

At Veliz’s trial, a criminalist from the police crime laboratory testified that, based on the .081 BAC at 3:32 a.m., Veliz’s BAC at the time of the stop would have been between 0.095 and 0.124. The jury found Veliz guilty of DWI.

On appeal, Veliz argued the criminalist’s testimony regarding his BAC was not admissible. This is where retrograde extrapolation became important.

The issue in a DWI case is the BAC at the time the defendant was driving. The blood sample is often obtained hours after the arrest. The process for estimating a BAC at the time of arrest based on a blood sample drawn later is known as retrograde extrapolation: a BAC at one point in time (3:32 a.m. for Veliz) is used to estimate the BAC at a time in the past (12:05 a.m. for Veliz).

Mata Factors Must Be Proven In Order to Apply Retrograde Extrapolation in Texas DWI Cases

Texas case law allows retrograde extrapolation testimony if the expert witness understands how to apply and how to clearly explain the process. In assessing such testimony, courts consider the time between the offense and the blood test, how many tests are administered and at what intervals, and any characteristics of the individual that were considered, including weight, gender, drinking pattern, tolerance for alcohol, amount of alcohol consumed, type of alcohol consumed, time of the last drink and what food was consumed. These are known as the Mata factors, based on the case in which they were first applied.

The Mata factors are important because different individuals’ bodies absorb and eliminate alcohol at different rates. And calculating a BAC retroactively requires knowing whether the individual was in the absorption phase (increasing BAC) or in the elimination phase (declining BAC). While not every factor must be known, Texas case law requires that if only one test is performed some time after the alleged offense, retrograde extrapolation is reliable only if many of the factors are considered.

The Court found the criminalist did not know many of Veliz’s relevant characteristics–his drinking pattern, the time of his first or last drink, or whether he had eaten recently. The criminalist testified she did not know the Mata factors for retrograde extrapolation. She also testified–incorrectly–that all she needed to perform a retrograde extrapolation was the time of the stop and the time of the blood draw. Because the criminalist did not understand and could not explain the subtleties of retrograde extrapolation, the court reversed the verdict and remanded for a new trial.

Some people believe refusing a blood test when arrested for DWI is a good strategy because any delay will result in a lower (and unreliable) BAC. However, a Fort Worth Criminal Defense Attorney will advise that a BAC based on blood drawn several hours after the arrest can be used to calculate a BAC at the time of arrest that will be admissible in court if the retrograde extrapolation appropriately considers some or all of the Mata factors.

On the other hand, if an individual is on trial for DWI, his or her Fort Worth Criminal Defense Attorney should carefully question any BAC evidence, particularly if it is based on a blood draw that occurred some time after the arrest. Retrograde extrapolation is not an exact science, and a jury will be allowed to hear testimony only if the extrapolation is appropriately performed and explained.

Contact the Experienced Fort Worth DWI Attorneys at Barnett Howard & Williams PLLC. (817) 993-9249

Our Tarrant County DWI attorneys are experienced in the science behind DWI and retrograde extrapolation for determining BAC. If you have been arrested for DWI, please contact us today for a FREE consultation of your case. Call (817) 993-9249 and set up an office consultation in Fort Worth, Keller, or Grapevine.

Jun 17
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The Confrontation Clause and Testimony From a Supervising DNA Analyst

By Confrontation Clause

As Fort Worth criminal defense attorneys, we often encounter confrontation issues during trial. The Confrontation Clause of the Sixth Amendment gives a defendant the right to confront witnesses against him. This provision prevents admission of a “testimonial” statement–a formal statement similar to trial testimony–unless the person who made the statement can be cross-examined or is unavailable but was previously cross-examined (in a deposition, for example). In the absence of cross-examination, a criminal defense attorney in Fort Worth would object to admission of the statement as evidence.

In Paredes v. State, the Court of Criminal Appeals considered how the Confrontation Clause applies to DNA testimony based on computer-generated data obtained through batch DNA testing. During a robbery, two victims were shot and killed. Jovany Paredes asked Jessica Perez to wash the shirt he was wearing during the robbery. Instead, Perez gave the shirt to police, who sent it to a lab for DNA testing. DNA from blood on Paredes’s shirt matched one of the victims.

At trial, Robin Freeman, the lab director, explained that DNA testing involves four analysts. The fourth analyst interprets raw data from a computer to determine whether there is a DNA match. In Paredes’s case, Freeman herself compared the DNA profile from the blood stain to Paredes’s DNA profile. Freeman testified that she did not personally observe each of the analysts performing the first three steps but that any problem in the analysis would have been obvious. Freeman testified that the ultimate opinion was hers and that she was testifying regarding her opinion.

Paredes’s defense attorney objected, arguing that he was entitled to cross-examine the other analysts. The State said those analysts just took “physical stuff,” placed it into instruments and applied chemicals. Freeman, the State said, was the one who did the interpretation that was presented to the jury. The judge agreed with the State, and Paredes was convicted of capital murder.

The Court of Appeals affirmed, holding that Freeman’s testimony did not violate the Confrontation Clause. After the Court of Appeals decision, the CCA decided in Burch v. State that admission of a drug test lab report did violate the Confrontation Clause because the testifying witness stated that the report was a “surrogate” for the technician who performed the test. Paredes appealed based on Burch. The CCA vacated the Court of Appeals decision and remanded the case to consider whether Burch affected the decision in Paredes.

The Court of Appeals made the same decision the second time, distinguishing Paredes, where the lab director had knowledge of the tests used and conducted the crucial analysis, from Burch, where the testifying lab supervisor had not observed or performed any part of the drug test or its analysis. Because Paredes’ attorney had the opportunity to cross-examine the person who conducted the actual analysis that linked him to the crime, Paredes’ Confrontation Clause rights had not been violated.

Paredes appealed to the CCA again. The Court reviewed three U.S. Supreme Court cases involving forensic reports. In the first two cases, the Supreme Court had found the forensic reports inadmissible because only a “certificate of analysis” was presented as evidence and a testifying witness had not actually performed the test.

In the third case, a DNA case, an outside forensics specialist testified that the lab-created DNA profile matched the defendant’s DNA profile. The Supreme Court held that this evidence did not violate the Confrontation Clause.

Based on the Supreme Court cases (Melendez-Diaz and Bullcoming) and the decision in Burch, the CCA ruled against Paredes. The CCA relied on the fact that Freeman, the testifying witness, had actually performed the crucial analysis and had testified to her own conclusions. Further, the lab director had testified regarding the quality assurance system at the lab that would alert the director if the test were done improperly. The CCA also distinguished this case because Freeman had relied on raw, computer-generated data in reaching her conclusions, rather than relying on another analyst’s report. Because Paredes was given the opportunity to question Freeman regarding her opinion, the CCA held that his Confrontation Clause rights were not violated.

A Fort Worth criminal defense attorney whose client is facing forensic expert testimony will carefully consider Paredes. Challenges to DNA evidence may be more difficult, particularly if the testifying witness is the individual who actually translated the raw data into a conclusion regarding a DNA match. A criminal defense attorney in Fort Worth will carefully monitor the application of Paredes to cases with similar, yet different, facts.

Nov 14
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A Harmful “Synergistic Effect” Instruction

By DWI

What is a Synergistic Effect in a Texas DWI case?

You are further instructed that if a person by the use of medications or drugs renders herself more susceptible to the influence of intoxicating alcohol than she otherwise would be and by reason thereof became intoxicated from the recent use of intoxicating alcohol, she is in the same position as through her intoxication was produced by the intoxicating alcohol alone.

That sentence, in the world of Texas DWI litigation, is known as the “synergistic effect” instruction.  It is typically given to a jury in a DWI case that involves both the use of alcohol and drugs (including over-the-counter medications).  The Texas Court of Criminal Appeals has held that the synergistic effect instruction does not expand on allegations of intoxication due to alcohol, which means that a person charged with DWI due to intoxication from alcohol alone, may be convicted if the State proves that the intoxication occurred due to a combination of alcohol and drugs.  See Gray v. State, 152 S.W. 3d 125 (Tex.Crim.App. 2004).

Last week, the CCA revisited this issue (somewhat) in Barron v. State, a case on appeals from the 5th District Court of Appeals (Dallas).  In Barron, there was minimal evidence of intoxication and the defendant did not submit to a breathalyzer test.  However, the arresting officer found (but failed to seize) what he identified as hydrocodone in the defendant’s vehicle.  Although there was no evidence at trial that (1) the substance in the pill bottle was in fact hydrocodone, or (2) the defendant actually ingested the alleged substance, the trial court, nonetheless (and over defense objection), gave the synergistic effect instruction to the jury.  In closing argument, the state relied on the scant evidence of drug/alcohol combination and the defendant was convicted.

On appeal, the 5th COA held that the trial court erred by giving the synergistic effect instruction when there was no evidence in the record to support the theory that the defendant ingested hydrocodone.  The 5th COA further held that the erred was harmful.  On petition to the CCA for discretionary review, the State relied on the CCA’s holding in Gray to argue that because the synergistic effect instruction does not expand the allegation of intoxication due to alcohol, then there was no error (or it was harmless).

The CCA agreed with the COA that it was error for the trial court to give the instruction when there was no evidence in the record that the defendant ingested a drug in combination with her consumption of alcohol.  The CCA, however, disapproved of the manner in which the 5th COA conducted the harm analysis, noting that the COA’s harm analysis “simply repeats its error analysis.” A proper analysis, the CCA explains:

should follow the guidelines of Almanza, assaying the degree of harm ‘in light of the entire jury charge, the state of the evidence, including the contested issues and weight of probative evidence, the argument of counsel and any other relevant information revealed by the record of the trial as a whole.’

The CCA concluded that the error was harmful in this case because it emphasized the State’s theory of the case (that the defendant was intoxicated due to a combination of alcohol and drugs), when the state of the evidence did not support this theory.

Takeaway: The “synergistic effect” instruction is not an all-out license for the State to pursue a theory of intoxication that it did not charge in the indictment/information.  The theory must be supported by the evidence, rather than a mere hunch.

Presiding Judge Keller dissented, noting that the synergistic effect instruction in this case might not have been error under the CCA’s recent holding in Ouellette v. State (2011 Tex. Crim. App. LEXIS 1373 (October)), a case that had not been published when the COA decided this case.  She would have vacated the COA decision and remanded the case for reconsideration in light of Ouellette.

Judge Meyers dissented and would send the case back for the COA to conduct a legal sufficiency review rather than a harm analysis.

Judge Keasler also dissented, but without a written opinion.

Jul 28
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Fort Bend County Loses the Dog Scent Lineup Issue Again

By Dog Scent Lineup

Last year, I posted about a murder case wherein a Fort Bend County dog handler used three bloodhounds to conduct a “dog scent lineup” to match a suspect’s body scent to the scent of certain evidence from the crime scene.  In that case, the CCA ruled that the scent evidence was not enough to establish that the suspect had committed the murder.  The CCA did not comment on the admissibility of scent lineup evidence.

Today, the First District Court of Appeals (Houston) issued an opinion in State v. Dominguez, another case involving the Fort Bend County dog handler.  Much like the last case I posted about, the dog handler was used to match a murder suspect’s scent with the scent of certain evidence from the crime scene.  This time, however, the scent lineup evidence did not even make it to the trier of fact.  After hearing the views of competing experts, the trial judge ruled that the evidence was inadmissible as unreliable.  Some of the flaws in the dog handler’s methodology that the court noted were:

  • He carries around his “blind” non-suspect scent samples (called foil samples) in ziplock bags;
  • His foil samples are old samples, while the scent sample of the suspect is fresh;
  • He does not do negative runs where the sample of the suspect is excluded;
  • He uses multiple dogs during each test rather than allowing the dogs to work alone; and
  • He is mostly self-taught and his methodology is something he created.

On appeal, the State argued that the trial judge abused his discretion in refusing to admit the evidence.  The First District upheld the trial judge’s ruling, holding that it was reasonable for the trial court of conclude that the scent lineup evidence was unreliable.

Now the courts have intervened twice to smack down the Fort Bend County dog handler’s “dog scent lineup” evidence.  The question is: will they keep using the dogs in Fort Bend or will there be three former police bloodhounds on Craigslist by the end of the week?