Ten years ago exactly — on Jan. 21, 2010 — the Supreme Court gave the green light to unlimited political expenditures by corporations, labor unions and nonprofit groups. The decision in Citizens United v. FEC, which said curbs on such spending violated the First Amendment, fundamentally changed the way elections are financed today.

A decade later the majority opinion in Citizens United is labeled, more often than any other single thing, as the ultimate antagonist of the democracy reform movement. The ruling has become so infamous it's used as shorthand for a campaign financing system that gives lopsided political advantage to the wealthiest over everyday citizens, including for reasons that have nothing to do with that case. That said, however, the decision has permitted groups that are not affiliated with any candidate or political party to pour almost $4.5 billion into the subsequent campaigns for president and Congress — an astonishing six times the total for all such independent expenditures in the two previous decades.

The 10-year anniversary has campaign finance experts all along the ideological spectrum reflecting on what the decision has meant for American politics, and what changes to laws and regulations might withstand court challenges and limit the impact of Citizens United in the decade ahead — on the assumption the ruling is on the books for at least that much longer.