Reduced to their ideal core, Minnesota political campaigns are conversations between candidates and voters. State campaign laws -- some ancient, some devised after Watergate showed how the conversation could be distorted by big money and unscrupulous players -- have worked fairly well to keep candidates and voters in control of their exchange.

Last week's 5-4 U.S. Supreme Court decision gives special interests greatly expanded opportunity to butt in. It struck down as a violation of the First Amendment attempts by government to bar corporations and labor unions from engaging in political advertising independent of that done by candidates.

As believers in the truth-revealing power of free speech, we don't share the degree of alarm the court's ruling caused among many stewards of democracy. Allowing businesses and unions the right to amplify their opinions during campaigns does not guarantee that their views will win over voters. What's more, denying those organizations the chance to advertise directly during campaigns has neither muted them nor blunted their considerable impact on public policy.

But if voters and candidates, not special interests, are to remain the dominant communicators in Minnesota campaigns, state lawmakers need to adjust state laws to account for the heightened campaign din that the high court's ruling invites. Within hours of the Supreme Court ruling, state Rep. Ryan Winkler, DFL-Golden Valley, laid out a four-point plan for lawmakers who want to keep candidates and voters in charge when state constitutional offices and legislative seats are on the line, as they are this year. It's a fine starting point for legislative action. Winkler's ideas:

• Require special interests to reveal their identities in every campaign ad and disclose the sources of their funds. State lawmakers have tried before to insist on the disclosure of the sources of noncandidate spending that aims to influence state elections. Each time, lower courts have found Minnesota's requirements inconsistent with freedom of speech. But in last week's decision, the U.S. Supreme Court held that governments can require public disclosure of the purchasers of political messages. Minnesota legislators ought to take that part of the new ruling and run with it.

• Modernize all disclosure deadlines to conform to the Internet communication age. Current laws were written with paper record-keeping and postal delivery schedules in mind. With all-electronic filing of state campaign finance records already set to become law in 2012, the obvious next step, particularly for statewide campaigns, should be to go public with political contributions and expenditures in "real time," or within a few days of their occurrence.

Similarly, the registration deadline for new purchasers of campaign ads ought to be tightened. It was the extended grace period for new registrants with the state that allowed Texas multimillionaire Bob Perry, the financier of the 2004 anti-John Kerry "swift boat" smear, to buy $500,000 worth of anti-Mike Hatch ads at the close of the 2006 gubernatorial campaign and go undetected until after the election.

• Increase contribution limits for state candidates, so that larger donors feel less compelled to buy their own ads to aid the candidate of their choice. State contribution limits have not been adjusted in years; for legislative candidates, they sit at a modest $500. Doubling that amount makes sense.

Increasing how much candidates can spend and still qualify for public campaign financing may also be in order. But if Minnesota is going to preserve its nationally acclaimed system of offering candidates partial public financing of their campaigns in exchange for adherence to voluntary spending limits, one other step is needed:

• Restore the political campaign refund program that Gov. Tim Pawlenty killed via unallotment last year. That program reimbursed small individual donors who contributed to state candidates, up to $50 per individual or $100 per couple. It was an important incentive for candidates to enroll in the public financing program, since only gifts to participating candidates were eligible for refunds.

National observers have long hailed Minnesota's public campaign financing system as a model for keeping campaign costs low and special-interest influence small. But the system won't survive if candidates believe it puts them in a position to be drowned out by independent expenditures. In the wake of the U.S. Supreme Court ruling, some Minnesota candidates likely think they are in that position now.