(CN) - The Supreme Court on Thursday killed a central part of the McCain-Feingold campaign finance law and ruled that corporations may spend as much as they wish to support or oppose candidates for president and Congress. The 5-4 vote left intact limits on corporate gifts to individual candidates.
Writing in dissent, Justice John Paul Stevens said the majority "threatens to undermine the integrity of elected institutions across the nation."
But Justice Anthony Kennedy, writing for the majority, called the McCain-Feinberg's restrictions "censorship ... vast in its reach."
"By suppressing the speech of manifold corporations, both for-profit and nonprofit, the Government prevents their voices and viewpoints from reaching the public and advising voters on which persons or entities are hostile to their interests," Kennedy wrote.
Citizens United, a conservative nonprofit, filed suit after it was blocked from airing its scathing political film, "Hillary: The Movie," on pay-per-view television before the 2008 primary elections.
The group said the decision by the Federal Election Commission violated its free-speech rights. The movie features various pundits discussing Clinton's bid for the presidency.
Last year, a federal court in Washington, D.C., deemed the film corporate electioneering, saying it was "susceptible of no other interpretation than to inform the electorate that Senator Clinton is unfit for office, that the United States would be a dangerous place in a President Hillary Clinton world, and that viewers should vote against her."
The high court convened early to hear the closely watched First Amendment case, which had the potential to upend campaign-finance laws in 26 states.
The Bipartisan Campaign Reform Act of 2002, known as the McCain-Feingold law for its sponsors, bars companies from airing "any broadcast, cable or satellite communications" that refers to a candidate for federal office within 30 days of a primary or caucus or 60 days of a general election.
Citizens United urged the justices to decide the case on narrower grounds, arguing that "Hillary: The Movie" doesn't qualify as "electioneering communication" under campaign-finance law and that video-on-demand doesn't constitute a commercial broadcast.
But the Supreme Court said its ruling had to be broad, because a narrow decision would chill political speech.
"Any other course of decision would prolong the substantial nationwide chilling effect caused by [the law's] prohibitions on corporate expenditures," Kennedy wrote.
Kennedy said a broad approach required the court to tackle the validity of Austin v. Michigan Chamber of Commerce, a 1990 Supreme Court decision to uphold a Michigan campaign-finance law.
The majority said the court should return to pre-Austin precedents that rejected restrictions on corporate political speech.
"The purpose and effect of [McCain-Feingold] is to prevent corporations, including small and nonprofit corporations, from presenting both facts and opinions to the public," Kennedy wrote.
"When Government seeks to use its full power, including the criminal law, to command where a person may get his or her information or what distrusted source he or she may not hear, it uses censorship to control thought. This is unlawful. The First Amendment confirms the freedom to think for ourselves."
Justice Stevens, in his dissent, said nothing was being "banned," and the argument was simply over "whether Citizens United had a right to use the funds in its general treasury to pay for broadcasts during the 30-day period."
He said corporations and individual speakers need not be treated equally, and the majority's refusal to draw a distinction "blazes through our precedents."
He strongly disagreed with the court's decision to overrule Austin and parts of McConnell v. FEC, which relied on Austin.
"Our colleagues' suggestion that 'we are asked to reconsider Austin and, in effect, McConnell' would be more accurate if rephrased to state that 'we have asked ourselves' to reconsider those cases," Stevens wrote. He feared such a path would "do damage to this institution."
Justices Ruth Bader Ginsburg, Stephen Breyer and Sonia Sotomayor joined Stevens in dissent.