The Takings Clause of the Fifth Amendment provides that government may not take private property without just compensation. The courts have held that this clause requires government to compensate landowners for losses caused by government regulation in certain situations- most notably when regulation leads to a permanent physical invasion of property (1) or makes property worthless (2).
But after having taught Kelo to law students several times over the past few years, I now realize that Kelo is much more complex. Kelo was a 5-4 decision, and Justice Anthony Kennedy wrote a separate concurrence. Because Justice Kennedy was the “swing vote”, his decision predicts future Court decisionmaking more accurately than the Court’s primary opinion, because a taking which fails to satisfy Kennedy might not be able to get five votes in the Supreme Court.