In Commonwealth v. Loeper, 541 Pa. 393, 663 A.2d 669 (Pa. 1995), the Supreme Court, applying concluded that because Loeper's blood alcohol content (BAC) did not represent a substantial departure from the legal limit, and there was a two-hour delay between driving and testing, the inference of guilt was too weak to support an (a)(4) conviction without relation-back evidence. Accordingly, the Court noted, had Yarger and Subsection (a)(5) been the law at the time of Loeper's trial, evidence of Loeper's .141% BAC two hours after driving would have been sufficient by itself to sustain his conviction under (a)(4). Loeper, at 674 n.7. The Court acknowledged that evidence of a blood alcohol content equal to or above the legal limit was sufficient to establish a prima facie case; the defendant would then be permitted to present expert testimony in rebuttal. Loeper, at 674 n.7.