Gas Headspace Chromatography Test Meets Frye-Mack; Results of Urine Test Are Admissible

State v. Edstrom, Minn.Ct.App., 12/21/2010.  A Carver County Deputy arrested Ms. Edstrom for driving while impaired; she consented to a urine test, which she provided.  She did not first void her bladder before providing the test sample.  The BCA ran the sample through something called a “gas headspace chromatography,” which said that the alcohol concentration from the sample was 0.08.

Ms. Edstrom asked for a Frye-Mack hearing to evaluate gas headspace chromatography.  The state objected but the trial court held one anyway.  Although the court of appeals has issued several opinions that upheld either the admission or exclusion of “first-void urine” tests, neither that court nor the supreme court had evaluated such evidence under Frye-Mack.  Now it has.

So, just what is this contraption?  Here’s how the appellate court describes it:

Gas headspace chromatography involves the isolation of compounds contained in a urine sample and the measurement of the concentration of each compound. The urine sample is placed in a vial and diluted with a liquid solution. Then, the vial is heated until the urine sample equilibrates, meaning that the gas and liquid forms of the compounds in the liquid solution reach a constant ratio. Next, the vapor is transferred to a gas chromatography column. The vapor travels through the column, and as it does so, the compounds in the vapor separate from each other and attach to the column. A detector identifies each of the compounds and measures the quantity of the compounds in the urine sample.

The appellate court concluded that gas headspace chromatography is generally accepted in the scientific community whether testing “first-void” or “later-void” samples.  The court also rejects various defense expert contentions about the test’s reliability.  So, the test passes the Frye-Mack requirements.

Which is what the trial court had actually ruled, notwithstanding which the court then suppressed the evidence.  The trial court said that the test result was but one factor to be considered in determining impairment but is not, itself, evidence of impairment.  The trial court feared, however, that a jury would reach just that conclusion, that the test result meant that Ms. Edstrom was impaired, no matter what evidence she submitted.  The prejudicial effect of admitting the tests result thus outweighed its probative value.

Not so fast.  Relevant evidence, which the test result is, is not excludable unless it poses a risk of unfair prejudice.  Rule 403 says that relevant evidence may be excluded “if its probative value is substantially outweighed by the danger of unfair prejudice, confusion of the issues, or misleading the jury…”  That’s not the case here for three reasons:  a defense expert, an instruction to the jury, or defense closing argument.  The test result is in.