Fifty years ago today, in Heart of Atlanta Motel v. U.S., the Supreme Court declared constitutional Title II of the Civil Rights Act of 1964, which forbade discrimination by privately owned businesses, such as motels, theatres and restaurants, that serve as public accommodations.
This landmark unanimous decision established the important precedent that the Commerce Clause of Article I, Section 8 of the Constitution authorizes Congress to prohibit racial (and other forms) of discrimination not only by government, but also by privately owned businesses. This was a crucial step in the movement to dismantle the Jim Crow system.
More on the Civil Rights Act of 1964 here and more on the Heart of Atlanta Motel decision here and here. For recent scholarly analyses of the enduring constitutional issues addressed (but not settled) in the case, see this, this and this.