On June 23, 2017, the U.S. Supreme Court decided Murr v. Wisconsin, No. 15-214, 2017 WL 2694699 (U.S. June 23, 2017), which presented perhaps the most important issue of regulatory takings law that the Court has never addressed – the “relevant parcel” or “parcel-as-a-whole” issue. That issue, which arises in many regulatory takings cases, is how a court should define the property at issue for purposes of assessing whether a regulatory imposition constitutes a taking of that property. The issue is important, and indeed can be determinative, because defining the relevant property narrowly will concentrate the impact of the regulatory imposition and thus make it more likely to constitute a taking. Conversely, defining the relevant property broadly will mitigate the severity of a regulation’s impact on the “parcel-as-a-whole,” making a taking of the whole parcel less likely.