Corruption breaks the constitutionally necessary “chain of communication” between the people and their representatives. It derails the essential speech-to-government-action tie. Where enough money calls the tune, the general public will not be heard. Insofar as corruption cuts the link between political thought and political action, a free marketplace of political ideas loses its point. That is one reason why the Court has stressed the constitutional importance of Congress’ concern that a few large donation snot drown out the voices of the many.
— Excerpt from the dissent in McCutcheon v. Federal Elections Commission, authored by Justice Breyer and signed by Justices Sotomayor, Kagan, and Ginsburg.