In 2014,[1] the US Supreme Court struck down the aggregate limit on the amount individuals may contribute in total to political parties and federal candidates on the grounds that aggregate limits on campaign contributions were unconstitutional under the First Amendment, as they constituted a violation of freedom of speech.
[1] McCutcheon v. Federal Election Commission, 572 U.S (2014). Available at: http://www.supremecourt.gov/opinions/13pdf/12-536_e1pf.pdf
