...[T]he Supreme Court agreed to hear campaign-finance and tax cases whose outcome could hinge on the candidate filling the court's second vacancy.... Campaign-finance cases have revealed a philosophical split on the court, with more conservative justices, such as Antonin Scalia, considering political expenditures the functional equivalent of speech, and thus beyond state restriction. More liberal justices, such as Stephen Breyer, have viewed such regulations as lawful means to fight political corruption and keep moneyed interests from drowning out other voices. One of the political cases challenges a provision of the McCain-Feingold law that prohibits corporations from direct expenditures on electioneering...