What Method Has the Legislature Provided by Which a Defendant May Challenge the Reliability of BAC Test Results ?

In Commonwealth v. Speights, 353 Pa. Super. 258, 509 A.2d 1263 (Pa. Super. 1986), appeal denied, 517 Pa. 594, 535 A.2d 83 (Pa. 1987), the defendant was charged under Section 3731(a)(4), having had a BAC of .12% two hours and forty-five minutes after he drove. This Court concluded the evidence was sufficient to support an (a)(4) conviction without relation-back testimony. In so holding, we emphasized that the legislature has provided a method whereby a defendant may challenge the reliability of BAC test results. See 75 Pa.C.S. 1547. The Court further observed: Subsection 1547(h) of the Vehicle Code allows a defendant to introduce into evidence the results of an additional blood alcohol test performed by a physician of the defendant's own choosing. At trial, the results of a test, as indicative of blood alcohol content at a relevant point in time, may be attacked or contradicted by any competent evidence. The weight to be accorded test results then properly rests with the finder of fact. Accordingly, we hold that blood alcohol test results can--by themselves, without explanation by expert testimony--suffice to support a conviction under subsection 3731(a)(4) but that blood alcohol test results do not compel the trier of fact to find a defendant guilty of violating subsection 3731(a)(4) where there is competent evidence of record challenging said test results. Speights, at 1267.