http://www.slate.com/articles/news_and_politics/jurisprudence/2015/06/gay_marriage_supreme_court_ruling_how_skinner_v_oklahoma_laid_the_foundation.html

In its decision announcing marriage equality for gay and lesbian Americans on Friday, the Supreme Court relied on the 14^th Amendment’s Due Process Clause, which protects liberty, and its Equal Protection Clause, which outlaws state discrimination. Most importantly, the court pointed to a “synergy” between the two clauses. To fully understand that synergy, which lies at the core of the court’s ruling, you have to know the story of a chicken thief named Jack Skinner.