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The 'Extrapolation' or 'Relation Back' Defense

VTL § 1192-2 (Driving While Intoxicated per se) provides that “[n]o person shall operate a motor vehicle while such person has a .08 of one per centum or more by weight of alcohol in the person’s blood” (emphasis added). This statute requires the prosecution to establish that the driver had .08 or more BAC at the time of operation. However, because 10 NYCRR 59.5 only requires that s a single test be administered within two hours of the arrest (or a positive breath test screening), it is impossible for the trier of fact to determine whether the client’s BAC had risen or fallen between the time of operation and the time the breath test was administered. In certain cases, because of a relatively low breath score (e.g., .12% BAC) and the amount of time between the stop of the client’s vehicle and administration of the breath test, an argument may be made that the client had less than a .08% BAC while driving but had greater than a .08% BAC when tested.n People v. Mertz, 68 N.Y.2d 136 (1986), the Court of Appeals held that it was error for the trial court to refuse to allow counsel to argue that the defendant’s BAC was less than .10% at the time of operation:

“…proof of a breathalyzer reading .10 or more within two hours after arrest established prima facie a violation of Vehicle and Traffic Law § 1192(2) which, together with evidence of one or more of defendant’s deportment, speech, stability and the odor of his or her breath, is sufficient to sustain a conviction, absent evidence, expert or other and by whichever party produced, from which the trier of fact could conclude that the defendant’s BAC at the time of operation was less than .10. When, however, as here, such evidence has been presented, defendant must be permitted to argue its significance to the jury. Mertz, 68 N.Y. I2d at 146.

This is a very fact specific defense and may be considered in defending the client who is facing a VTL § 1192-2 charge