The Supreme Court ruled today that limits on political spending by corporations violate their right to free speech and therefore are unconstitutional.

Business groups praised the ruling, while campaign-finance reformers condemned it.

In a 5-4 decision, the court overturned past rulings that prohibited corporations or unions from buying ads expressly advocating the election or defeat of political candidates. The court also overturned a ban on corporate-funded issue ads that mention a candidate in the weeks prior to an election.

In the opinion written for the majority, Justice Anthony Kennedy said the government “may regulate corporate political speech through disclaimer and disclosure requirements, but it may not suppress that speech altogether.”

Using the power of the government to tell voters where they can get their information is “censorship to control thought,” Kennedy wrote. “This is unlawful. The First Amendment confirms the freedom to think for ourselves.”

Greg Casey, president and CEO of the Business and Industry Political Action Committee (Bipac), praised the ruling.

“The Supreme Court’s ruling frees American business from the yoke of second-class citizenship,” Casey said. “It returns the right of American business to talk about workplace issues and hold candidates accountable.”

“We applaud the Court for affirming that our system can only be made stronger through open and honest debate,” said Robin Conrad, executive vice president of the U.S. Chamber of Commerce's National Chamber Litigation Center.

The ruling “provides clarity and predictability for all entities—nonprofits, trade associations, labor unions, and corporations—that engage in the political process,” Conrad said.

Critics, however, contend the ruling will open the floodgates for corporate political spending at the expense of ordinary citizens.