(Image: Campaign finance via Shutterstock)The ruling opened the floodgates to fill campaign coffers with corporate cash and “enabled outside groups to run shadow campaigns for or against candidates of their choice,” according to a new study that analyzes where the money has come from so far in 2012.

The landmark 2010 Supreme Court ruling that struck down longstanding prohibitions on corporate political spending now accounts for 78 percent of spending by outside groups trying to influence the outcome of the 2012 election, according to a study conducted by the non-profit and non-partisan Sunlight Foundation.

About $365 million of the $465 million SuperPACs, unions, corporations, trade associations and non-profit groups spent this year opposing or supporting political candidates can be directly traced to the High Court’s decision in Citizens United v. Federal Election Commission, nearly double of what was spent in 2010 immediately following the ruling, says the analysis written by the Sunlight Foundation’s managing editor Kathy Kiely.

In the run-up to the 2008 presidential election, Citizens United, a conservative nonprofit corporation, wished to broadcast “Hillary: The Movie,” a documentary that profiled various scandals that unfolded during President Bill Clinton’s tenure in office and challenged Hillary Clinton’s record in the Senate. Citizens United had previously released the movie in theaters and on DVD, but wanted to broadcast the movie for on-demand viewers. Fearing that the broadcast would run afoul of the 2002 Bipartisan Campaign Reform Act’s (BCRA) prohibitions on corporate electioneering communications prior to elections, they brought suit in federal district court for an injunction against the law.

Because the movie was partially produced using corporate funds, a lower court ruled that it fell under the restrictions of the McCain-Feingold Act. Citizens United appealed that decision, and eventually wound up in the Supreme Court. After a first round of arguments, the justices made the unusual move of calling for a pre-term September re-argument this year, asking the parties to brief the court on whether the 1990 Austin decision, which justified the prohibition on corporate expenditures, should be overturned. On Thursday, five justices answered that question in the affirmative.

“Some members of the public might consider “Hillary” to be insightful and instructive; some might find it to be neither high art nor a fair discussion on how to set the nation’s course; still others simply might suspend judgment on these points but decide to think more about issues and candidates,” Kennedy wrote for the majority. “Those choices and assessments, however, are not for the government to make.”

According to the breakdown, Super PACs have spent about $272 million and unions, nonprofit organizations, corporations and trade associations have funneled about $93 million into campaign coffers. The latter are groups the Supreme Court said can spend unlimited amounts of funds and do not have to disclose the identities of their donors to the Federal Election Commission because of their tax status.

“This money enabled outside groups to run shadow campaigns for or against candidates of their choice,” according to the study. The spending also includes about”$4.1 million in expenditures for ‘electioneering,’ the term used for ads and political activities that focus on issues and policies in ways that not-so-subtly encourage voters to support or oppose a particular candidate.”

The study noted that a “deeper dive” into the data tracked by the Sunlight Foundation “shows that the latest uptick in outside spending is focused on congressional races: Even in presidential battleground states, almost all the spending by outside groups is focused on House and Senate candidates.”

During an online chat last month hosted by the social media website Reddit, President Obama said serious consideration should be given to “mobilizing a constitutional amendment process to overturn Citizens United.”

“Even if the amendment process falls short,” Obama said, in response to a Reddit user’s question about what the president would do to combat the influence of money in politics, “it can shine a spotlight of [sic] the Super PAC phenomenon and help apply pressure for change.”