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Explain the meaning and significance of the following passage from Justice Kennedy's majority opinion in Citizens United v. FEC (2010):
"If the First Amendment has any force, it prohibits Congress from fining or jailing citizens, or associations of citizens, for simply engaging in political speech. All speakers, including individuals and the media, use money amassed from the economic marketplace to fund their speech."
What was the Citizens United case about? And why, specifically, did the dissenting justices disagree with the majority? What was their argument?