That is covered here.
The Supreme Court also struck down what is called the ‘Millionaire’s Amendment’:
The Supreme Court on Thursday struck down a law meant to level the financial playing field when rich candidates pay for their own political campaigns.
The 5-to-4 decision, legal experts said, was significant for rejecting the rationale behind the law, known as the “millionaire’s amendment,” and for confirming the court’s continuing skepticism about the constitutionality of campaign finance regulations.
You can read the 39 page ruling here.
The whole background on the Davis v. FEC can be read here.
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