The protection of private property from government interference was of paramount concern to the founding generation, both while deciding whether to commit treasonous rebellion against the Crown in the 1770s or when debating the merits of a new constitution a decade later. The Framers recognized, however, that there would occasionally be times where private property needed to be requisitioned for public use, and so they provided the national government with the power to do so. They were careful, though, to make sure that this power would be limited, and included in the Fifth Amendment two requirements that the government must meet in order to take private property: the taking must be for a “public use,” and the owner must be provided “just compensation” for their property. Most state constitutions, including Mississippi’s, have similar clauses. Unfortunately, governments often do everything they can to get around the Fifth Amendment’s requirements, as the Mississippi Transportation Commission did when it tried to redefine the nature of Bay Point Properties’ land so as to make it effectively valueless for just compensation purposes. The land in question was originally owned by Wallace C. Walker. In 1952 the Mississippi State Highway Commission (later renamed the Mississippi Transportation Commission) built a toll bridge for U.S. Highway 90 on part of Walker’s land. The Commission used its eminent domain power to take a public easement over part of the land and built the bridge shortly thereafter. Bay Point Properties purchased the land in 1993 subject to the easement. When Hurricane Katrina destroyed the bridge in 2005, the Commission decided to relocate Highway and repurposed the old land as a public park, complete with a boat launch, concert lawn, playground, track, and restrooms. Under Mississippi state law in 1952 and longstanding common-law principles, the original easement terminated in 2005 when the land ceased being used for the highway, meaning that Bay Point legally held full, unencumbered title to the land from that point forward. Realizing this fact, Bay Point sued the Commission seeking just compensation for the property taken in order to build the park. A jury ruled in favor of Bay Point, but when the jury was asked to determine what compensation was due, the trial court directed the jury to value the property as if it was still encumbered by the 1952 highway easement, justifying its reasoning by pointing to a Mississippi statute that provides that no easement granted to the Commission would terminate unless and until the Commission acceded to termination of the easement (even though the law was amended to say so only in 1988, some 36 years after the Commission received an easement over Walker’s land in 1952). Under this instruction, the jury awarded Bay Point only a nominal amount of $500 (because a piece of property with a highway going across it is much less valuable). Bay Point appealed to the Mississippi Supreme Court, which affirmed the award, and now seeks U.S. Supreme Court review. The Cato Institute, joined by several likeminded organizations and law professors, has filed a brief in support of Bay Point and urging the Court to accept the case. We argue that the Mississippi Supreme Court’s ruling undermines due process’s general prohibition of retroactive lawmaking, undermines the separation of powers by usurping the fundamentally judicial function of ascertaining what constitutes just compensation, violates property owners’ Sixth Amendment right to have that determination made by a jury of one’s peers, and of course violates the Fifth Amendment’s demand that government entities only take private property for public use after the owner receives just compensation. The Supreme Court needs to make it emphatically clear that states can’t just legislate their way out of having to comply with the Fifth Amendment’s Just Compensation Clause.