The supreme court has struck down limits on individual campaign contributions, ruling that federal caps on combined donations to candidates, parties and political action committees are an unconstitutional infringement on free speech.



In a landmark judgment in favour of the rights of political donors, the conservative-dominated bench ruled five to four in favour of Alabama businessman Shaun McCutcheon, who funded 16 Republicans in 2012 but was prevented from supporting more by a $46,200 cap on overall donations.

A separate limit on how much can go to any single politician remains in place, but critics claim the ruling opens the way for wealthy individuals to buy influence on a national scale by bankrolling an unlimited number of candidates.

Chief Justice John Roberts rejected arguments made by the administration that lifting the aggregate limit would be a bigger infringement on the free speech of ordinary voters who cannot afford to influence politics in the same way.

Congress “may not … regulate contributions simply to reduce the amount of money in politics, or to restrict the political participation of some in order to enhance the relative influence of others,” said Roberts.

The ruling prompted a relatively muted response from Barack Obama, who was travelling to Michigan for the latest in a series of record-breaking political fundraisers this year to support Democratic candidates in November's midterm elections.

“We are still reviewing the details of the ruling that was issued today by the supreme court … We are disappointed by the decision,” said White House deputy spokesman Josh Earnest in a gaggle with reporters on Air Force One.

Justice Roberts' opinion was joined by Antonin Scalia, Anthony Kennedy and Samuel Alito, and supported by the fifth conservative justice Clarence Thomas.

But in a blistering dissent, the four liberal justices on the bench accused their colleagues of “misconstru[ing] the nature of the competing constitutional interests at stake” and “understat[ing] the importance of protecting the political integrity of our governmental institutions."

Their ruling “creates a loophole that will allow a single individual to contribute millions of dollars to a political party or to a candidate’s campaign,” wrote Justice Stephen Breyer.



"Taken together with Citizens United v Federal Election Commission, today's decision eviscerates our nation's campaign finance laws, leaving a remnant incapable of dealing with the grave problems of democratic legitimacy that those laws were intended to resolve," he added.



Some independent politicians argue that only radical overhaul of US campaign finance can salvage a system they claim has lost credibility among many voters.



“If we are to save American democracy so that the principle of one person one vote means anything, we need to overturn Citizens United and McCutcheon and move to public funding of candidates,” Vermont senator Bernie Sanders told MSNBC.



“Freedom of speech, in my view, does not mean the freedom to buy the United States government,” he added in a statement attacking the decision.

But Republicans viewed the court ruling as a breakthrough in their long-running campaign to get donations treated as an equal form of free speech.

“You all have the freedom to write what you want to write, donors ought to have the freedom to give what they want to give,” House speaker John Boehner told reporters after a party meeting.

RNC chairman Reince Priebus, who supported the McCutcheon appeal, said it was “an important first step toward restoring the voice of candidates and party committees and a vindication for all those who support robust, transparent political discourse”.

“I am proud that the RNC led the way in bringing this case and pleased that the court agreed that limits on how many candidates or committees a person may support unconstitutionally burden core first amendment political activities. When free speech is allowed to flourish, our democracy is stronger,” he added in a statement.

Roberts, known as a fierce defender of free speech provisions in the first amendment of the constitution, appeared to agree.

"Money in politics may at times seem repugnant to some, but so too does much of what the First Amendment vigorously protects," he concluded.



The case, which was supported by the Republican National Committee, follows the Citizens United ruling in 2010 that upheld the rights of corporations to make campaign contributions and unleashed a record wave of new money into the 2012 presidential election.

It also follows a clutch of corruption investigations by federal prosecutors against politicians such as Washington mayor Vincent Gray and Virginia governor Bob McDonnell, who received money from local businessmen they claim was in accordance with accepted campaign finance practices.