Several provisions of the Bill of Rights seem to rely on common law concepts to define the rights they protect, such as the Fourth Amendment's protection of "persons, houses, papers, and effects" and the Fifth Amendment's protection of "property." A few years ago, I wrote (with James Stern) an article arguing that the Fourth Amendment should be understood to rely on positive law—the law of the specific jurisdiction in which the search or seizure took place—to bound what counts as a search or seizure. (Orin vehemently disagrees.) But we noted one important limit to the use of positive law—one should look to the law that would bind ordinary private parties, not the law that specifically binds the government. After all, if the government tries to give itself a special legal privilege to commit batteries and trespasses, that is exactly what the Fourth Amendment limits.
Earlier this year, Danielle D'Onfro and Dan Epps wrote an interesting article that the Fourth Amendment should be understood not in light of a specific state's law but in light of general law—the unwritten, transjurisdictional law that was ubiquitous in federal courts during the era of Swift v. Tyson, before the revolutionary decision in Erie Railroad v. Tompkins. And while those pieces are about the Fourth Amendment specifically, the same kind of debate could translate to the Fifth Amendment's provisions as well.
In light of that background, I was especially interested in the Court's decision last week in Tyler v. Hennepin County. As readers surely know from Ilya's many posts on it, Tyler is a takings case, where Minnesota law defines away a homeowner's property rights in a way that would make it easy for the state to circumvent the just-compensation requirement. Thus, Chief Justice Roberts explains for the Court, it cannot rely purely on state law:
