Garba wanted to present testimony from two expert witnesses about possible reliability problems with the gas chromatography tests of his blood, but the circuit court wouldn’t let him. The court of appeals holds the circuit court properly exercised its discretion and rejects Garba’s claim the ruling violated his right to present a defense.
Garba’s blood was drawn after his arrest for OWI. The day the State Hygiene Lab tested his blood, several chromatograms from tests of blood samples other than his showed a series of so-called “jagged humps,” which basically means the chromatograms were showing readings for alcohol before the device would have had any alcohol to measure. The cause of these jagged humps is unknown, though the lab calibrated the testing equipment daily and monitored its performance throughout the testing day. (¶¶2-4).
In order to undermine the accuracy and reliability of his results, Garba wanted to call two expert witnesses to testify that the presence of jagged humps on some chromatograms created reliability issues with all of the results. But the experts admitted a level of uncertainty in their opinions. One said the appearance of the jagged humps before the results for alcohol meant they “would not directly interfere with an ethanol determination,” and she could not say whether the jagged humps produced a false positive or negative, or whether the humps had any effect whatsoever on the accuracy of the test. The second also admitted he could not say to a reasonable degree of scientific certainty that Garba’s test results were either accurate or inaccurate. (¶¶5-6).
The court of appeals holds the circuit properly excluded the experts’ testimony under § 907.02(1), “[t]he goal [of which] is to prevent the jury from hearing conjecture dressed up in the guise of expert opinion,” State v. Giese, 2014 WI App 92, ¶19, 356 Wis. 2d 796, 854 N.W.2d 687, and under § 904.03:
¶14 …. Although the experts concluded the jagged humps rendered Garba’s test results unreliable, the [circuit] court observed that this conclusion was backed, not by evidence, but speculation in the absence of evidence. The court expressly relied on the fact that “[n]either one of Mr. Garba’s experts … could opine to a reasonable degree of scientific certainty that the results were inaccurate, or that the jagged hump phenomenon— which was not even present on Mr. Garba’s test results—in any way impacted the test results on Mr. Garba’s sample.” The court also noted that the testimony was developed specifically for litigation and had not been subjected to peer review…. Accordingly, the court concluded that the opinions were not sufficiently reliable and would not be helpful to the jury.
¶15 The court separately concluded that Wis. Stat. § 904.03 provided an independent ground to exclude the evidence. It found that the testimony would invite the jury to speculate that Garba’s test was unreliable despite the experts’ inability to say whether the jagged humps had any effect at all on the test results. Hence, the circuit court concluded that the probative value was outweighed by the danger of unfair prejudice.
Nor did the exclusion of the experts violate Garba’s right to present a defense. Under State v. St. George, 2002 WI 50, ¶54, 252 Wis. 2d 499, 643 N.W.2d 777, excluding defense evidence may violate the right to present a defense if the evidence was admissible, necessary to the defense, and its probative value outweighs the danger of unfair prejudice. Garba can’t meet that last requirement:
¶21 …. It is true that both experts questioned whether the testing machines were functioning properly. But the experts based their conclusions not on evidence, but on a lack of evidence. Neither could say whether the jagged humps had any effect whatsoever on the results. Despite regular testing showing the results were within tolerances, the experts nevertheless concluded the results could not be trusted for reasons they could not explain. The testimony would have encouraged the jury to improperly speculate that the results were somehow suspect, despite a lack of evidence so indicating. …. Accordingly, Garba had no constitutional right to present it to the jury. ….
The court also rejects Garba’s contention that Wis. J.I.—Criminal 2663 improperly creates a presumption that the results of chemical tests for blood are accurate. (¶22). The court concludes the instruction “only informs the jury that the method used for testing is recognized to be reliable. It contains no presumption as to the accuracy or reliability of a particular test or machine.” (¶25). To the extent the instruction does create a presumption that a testing method is reliable, that isn’t problematic here because whether a testing method is reliable isn’t a fact necessary to constitute an OWI; it only provides evidence a jury can use to infer intoxication. (This issue will obviously be more salient in a PAC prosecution; Garba’s PAC charge was dismissed). (¶¶7, 26-29).