"The erroneous ruling… gives legal bribery a chance to prevail because almost all the candidates whether they are honest or not, and whether they are Democratic or Republican, depend on these massive infusions of money from very rich people in order to have money to campaign," Carter said in an interview on BBC Radio 4.
While some candidates, like current Republican forerunner Donald Trump, can spend their own money on campaigns, others require up to $100-200 million just to get a nomination from the Republican or Democratic parties, Carter said.
Carter, who served as US president between 1977-1981, stressed that candidates supported by the rich allow the rich to get richer after getting elected, while leaving the middle class out of the equation. The US middle class is stagnant or declining, he added.
The previous US presidential election in 2012, which became the most expensive in the country's history to date, saw political action committees (PACs) spend some $1 billion on the two forerunners Barack Obama and Mitt Romney, according to the Federal Election Commission (FEC). The total amount spent on the election amounted to $6 billion.
With the next US presidential election scheduled for November 2016, PACs have so far spent over $150 million since the start of 2016, FEC data showed. The only presidential candidate to reject the use of PAC funding during the 2016 election campaign is the long-time independent Senator Bernie Sanders.