On January 10, 2013, the Supreme Court of Virginia, in Ford Motor Co. v. Boomer, issued a unanimous decision announcing for the first time the proper causation standard to be applied in asbestos cases where a plaintiff alleges multiple sources of asbestos exposure. The Court began its analysis by recognizing that while Virginia is a traditional "but-for" jurisdiction, application of this standard in cases of multiple exposures would make it "difficult if not impossible" for a plaintiff to recover, as he or she would face the task of "proving that any one single source of exposure, in light of other exposures, was the sole but-for cause of the disease." The Court went on to also reject the "substantial contributing factor" standard employed by the trial court, a standard which, incidentally, has been routinely used by trial courts throughout the Commonwealth during the past decade. The Court reasoned that not only has it never invoked this standard in the history of its jurisprudence, but the term itself is fraught with problems: "We do not believe that substantial contributing factor has a single, common-sense meaning, and we conclude that a reasonable juror could be confused as to the quantum of evidence required to prove causation in the face of both a substantial contributing factor and a proximate cause instruction." The Court instead held that the standard to be applied is the "sufficient-to-have-caused standard" and the "multiple sufficient cause analysis." Pursuant to this new standard, an asbestos plaintiff must prove that it is more likely than not that exposure to a defendant's product occurred prior to the development of the plaintiff's illness and that such exposure alone was "sufficient to have caused the harm." In so holding, the Court invoked §§ 26 and 27 of the Restatement (Third) of Torts (and the Comments thereto) and confirmed its adherence to the Court's long-standing definition of proximate cause as set forth in Wells v. Whitaker, 207 Va. 616, 622, 151 S.E.2d 422, 428 (1966).