In a broad 5-4 decision in Citizens United vs. FEC, the Court found unconstitutional bans in the Bipartisan Campaign Reform Act that prevented corporate and labor union money from funding some kinds of political communication. Under the ruling these groups may now fund political advertisements out of their general treasuries.
The decision overturns Austin vs. Michigan Chamber of Commerce and part of McConnell vs. FEC, which separated individual and collective campaign contributions into two legal classes and restricted the latter. The court originally heard Citizens United last march on the narrow question of whether non-profit groups were subject to campaign finance restrictions, but reheard the case months later, this time focusing on the constitutionality of the restrictions themselves.
Justice Anthony Kennedy wrote for the majority and was joined by Chief Justice John Roberts, and Associate Justices Samuel Alito, Antonin Scalia, and Clarence Tohmas. Associate Justice John Paul Stevens wrote for the dissent.