Opinion ID: 2512385
Heading Depth: 1
Heading Rank: 9

Heading: Retrograde extrapolation and expert testimony in grand jury proceedings

Text: In Anderson v. State , this court recognized the use of retrograde extrapolation to estimate a defendant's BAC at the time of an accident. [42] In that case, a forensic chemist testified that the standard metabolism rate of alcohol is approximately 0.02 percent per hour, and he extrapolated backwards to estimate that the defendant's BAC was 0.128 when he was driving. [43] This court, however, has not addressed whether the State must present expert testimony or explain the extrapolation technique to a grand jury. We conclude that the presentation of such evidence is unnecessary in grand jury proceedings in light of the State's evidentiary burden. Burcham erroneously relies on a Texas Court of Criminal Appeals case, Mata v. State, [44] to support his argument that the State may not rely on retrograde extrapolation unless it presents an expert to testify on the technique. Burcham contends that Mata supports his proposition that expert testimony is required here because of the complexity of applying retrograde extrapolation in any given case. Specifically, Burcham points out that several factors affect the accuracy of retrograde extrapolation including: the length of time between drinking and the test; the number of tests and the time between each; and characteristics of the defendant such as age, weight, tolerance, the amount of alcohol consumed, and whether the person had eaten. [45] We conclude that Mata is unpersuasive here because the Mata court addressed whether expert testimony on retrograde extrapolation was reliable in a jury trial, [46] not whether expert testimony should be required when the State relies on retrograde extrapolation in grand jury proceedings. Mata is also distinguishable because the nature of the information regarding the BAC tests were different from the case at bar. In Mata, the defendant took two BAC tests minutes apart, over two hours after he was driving. [47] Because these tests were so close in time, the tests only served as a single test for determining whether Mata was still absorbing alcohol, meaning his BAC was rising, or was eliminating alcohol, meaning his BAC was dropping. [48] This contributed to the difficulty in estimating what his BAC was when he was driving. The Mata court held that an expert could create a reliable BAC estimation based on two BAC tests, taken a reasonable time after driving if a reasonable time elapsed between the tests, even with minimal knowledge about the defendant's personal characteristics. [49] In this case, Burcham took one BAC test about one hour after the collision and another about one hour later, which was lower. Thus, in this case, it was easier to infer that Burcham's BAC was dropping and to estimate that his BAC could have been 0.08 when he was driving. This court has deemed one officer's opinion testimony as sufficient to support an indictment. In Zampanti v. Sheriff, [50] this court held that a police officer's opinion that what the defendant possessed was marijuana was sufficient, by itself, to establish probable cause. In that case, the defendant represented to the officer that the substance in his possession was marijuana. [51] But this court held that even if that admission was not considered, the officer's testimony that the defendant's vehicle smelled of marijuana and the substance looked like marijuana was sufficient to support the indictment. [52] Although expert testimony generally would be required at trial to prove beyond a reasonable doubt that the substance was marijuana, we concluded that such testimony was not required at the grand jury. [53] Similarly, in this case, the two BAC tests suggested that Burcham's BAC was dropping and that it could have therefore been 0.08 when he was driving. We conclude that because the State's burden at a grand jury proceeding is to present slight or marginal evidence to support an inference that the accused committed the crime charged, specific scientific evidence and expert testimony concerning retrograde extrapolation are not required. [54] Such a requirement would place a tremendous burden on the State to produce, during grand jury proceedings, evidence addressing the many factors involved with retrograde extrapolation, as discussed above. [55] We further conclude that the State is not required to provide the grand jury with an instruction regarding retrograde extrapolation. We now address whether the State offered sufficient evidence to support Burcham's indictment for driving with a BAC of 0.08 or higher.