It is a promise of the Constitution that there is a realm of personal liberty which the government may not enter. We have vindicated this principle before. Marriage is mentioned nowhere in the Bill of Rights and interracial marriage was illegal in most States in the 19th century, but the Court was no doubt correct in finding it to be an aspect of liberty protected against state interference by the substantive component of the Due Process Clause in Loving v. Virginia, 388 U. S. 1, 12 (1967) (relying, in an opinion for eight Justices, on the Due Process Clause).
Planned Parenthood of S.E. Pa. v. Casey, 505 U.S. 833, 848 (1992)
« Why he wrote that 1885 law review article on the relation of the judiciary to the Constitution, according to William Montgomery Meigs in 1919
A reminder about marriage and personal liberty, from the plurality opinion in Casey
January 13, 2013 by Kevin C. Walsh