Pennsylvania v. Nelson

In the mid-1950s, the liberal Court led by Chief Justice Warren came head-to-head with the conservative paranoia that helped fuel the communist witch hunt led by Senator Joseph McCarthy. Those who believed that there was an international communist conspiracy to overthrown the U.S. government, and who agreed with McCarthy that communists had infiltrated all sectors of American society, were often the same people who bitterly denounced the Warren Court. Feelings ran so high that the chief justice's public appearances were sometimes boycotted, and movements to impeach him cropped up from time to time. For the most ardent anti-communist warriors in the Cold War, Warren's opinion in Nelson--which seemed the equivalent of letting an admitted communist off on a technicality--was the last straw.

A powerful movement sprang up in Congress to pass legislation that would overturn Nelson and prevent anything like it from happening again. However, cooler heads eventually prevailed. The attempt to overturn Nelson was tied to a broader legislative proposal to block all implied federal pre-emption of state laws. Congress soon realized that the "technicality" which had freed Steven Nelson was in fact an important principle: the effectiveness of federal legislation is undermined when comparable but conflicting state statutes are permitted to dominate. Even some of those in Congress who were advocates of states' rights (the principle that individual state sovereignty should usually prevail over a strong federal government) found the prospect of doing away with federal preemption undesirable.

Although Nelson spelled the end for the Pennsylvania antisedition statute, other state antisedition laws remained on the books. Later, they were revived by various state legislators to justify arrests of demonstrators during the civil rights movement of the 1950s and 1960s and the anti-Vietnam War protests of the 1960s and 1970s.