Adair V. United States

Adair v. United States, 208 U.S. 161 (1908), is a United States Supreme Court case which upheld "yellow-dog" contracts that forbade workers from joining labor unions. The decision reaffirmed the doctrine of freedom of contract which was first recognized by the Court in Allgeyer v. Louisiana (1897). For this reason, Adair is often seen as defining what has come to be known as the Lochner era, a period in American legal history in which the Supreme Court tended to invalidate legislation aimed at regulating business.

In earlier cases, the Court had struck down state legislation limiting the freedom of contract by using the due process clause of the Fourteenth Amendment, which only applied to the states. In Adair the doctrine was expanded to include federal legislation by way of the due process clause of the Fifth Amendment.