Is retrograde extrapolation relevant in determining whether a defendant was driving under the influence?

The other cases cited by defendant are not helpful to his claims. In People v. Emery (Colo. 1990) 812 P.2d 665, defendant argued the prosecution's expert testimony on retrograde extrapolation was scientifically unreliable. The court declined to address the issue, and held defendant's conviction for driving under the influence was supported by the statutory inference that if a chemical test reveals the defendant's blood alcohol level was above the legal limit within a reasonable time after the alleged offense, the jury may infer defendant was driving under the influence. Emery held that since defendant's conviction was supported by the statutory inference, the prosecution's expert testimony regarding retrograde extrapolation was irrelevant and any error was harmless. (Id. at pp. 667-668.)