One of the biggest issues from the 2016 presidential election is campaign finance reform.
The issue of campaign finance is not a new issue to the decade but arrived in the 1970s with the passage of the Federal Election Campaign Act. One of the major parts of the act included the formation of a Federal Election Commission that would examine claims of violating campaign finance regulations. In the 1976 case Buckley v. Valeo, the Supreme Court determined that money contributions can be considered as "speech" under the First Amendment. The court struck down the act's limit on candidates spending their own money on electoral campaigns. As a result, individuals who are billionaires could spend a large amount of their own fortune funding a campaign without a limit.
The Supreme Court also struck down limits on how much a campaign could spend, as the reasoning didn't justify an aim at preventing corruption. However, the provision that limited individual contributions to campaigns was upheld along with the Federal Election Commission.
Further cases have upheld further conditions and amendments to campaign finance reform. In 1990, the court upheld the Michigan Campaign Finance Act which banned corporations from making independent expenditures to candidates in Austin v. Michigan Chamber of Commerce. In 2002, Congress passed the Bipartisan Campaign Reform Act or otherwise known as the McCain-Feingold Act. The act tackled the issue of soft money by prohibiting political parties from raising money that would not be subject to federal oversight. The legislation also limited when ads funded by corporations and non-profits could invoke a candidate's name before an election. The court upheld the restrictions in McConnell v. FEC.
It seemed that the court was very willing to uphold limits on corporate and non-profits until the rise of the 2010 case Citizens United v. FEC. They partially overturned McConnell v. FEC and fully overturned Austin v. Michigan Chamber of Commerce. The court fully recognized that campaign contributions constituted protection under the First Amendment. As a result, the Supreme Court struck down independent expenditure limits on corporations and non-profits.
This has allowed for a proliferation of outside donations into various political campaigns.