United Building & Constr. Trades Council of Camden Cty. v. Mayor and Council of Camden

For over a century the underlying meaning of the Privileges and Immunities Clause of the Constitution’s Article *224IV1 has been regarded as settled: at least absent some substantial, noninvidious justification, a State may not discriminate between its own residents and residents of other States on the basis of state citizenship.2 See generally Hicklin v. Orbeck, 437 U. S. 518, 523-526 (1978); Toomer v. Witsell, 334 U. S. 385, 395 (1948); Hague v. CIO, 307 U. S. 496, 511 (1939) (opinion of Roberts, J.); Slaughter-House Cases, 16 Wall. 36, 77 (1873); Paul v. Virginia, 8 Wall. 168, 180 (1869).

Today,…