Mathias Hong has posted this draft on SSRN. Here is the abstract:

If freedom of speech protects a marketplace of ideas – what is its proper currency? Is it only the force of the arguments brought forth – or is it money as well? For the current majority of the U. S. Supreme Court the answer under the U. S. Constitution seems clear: Freedom of speech must include the right to unfettered use of money in the competition. For the Court, the marketplace of ideas turns into a literal, economic marketplace. In what follows I will agree with most American scholars who sharply criticize this reading of the First Amendment. I will join in this critique, however, as somebody who genuinely admires the strong protection of free speech in the United States. I think Europe stands to learn a lot from the American model – but I agree with most scholars in the United States that the Supreme Court’s campaign finance decisions, especially since Citizens United (2010), do not do justice to that worthy American free speech tradition itself.