Fans of deciding elections by majority rule -- including this newspaper -- have been increasingly interested in instant runoff voting (IRV). That's the vote-by-number system that re-sorts and recounts ballots, dropping the low vote-getter each time, until one candidate emerges with 50 percent plus one of the votes cast.

It's a system approved by Minneapolis voters in 2006 for implementation in city elections, beginning in 2009 or as soon thereafter as the City Council deems doable.

On today's Opinion Exchange page, Hamline Prof. David Schultz weighs in on a question raised recently by a letter from Assistant Attorney General Christie Eller to Secretary of State Mark Ritchie. Might instant runoff voting as contemplated in Minneapolis be unconstitutional?

Eller raises that prospect, with lots of modifiers and caveats. Schultz makes a vigorous argument to the contrary.

The fact is, there is no way of establishing whether instant runoff voting is constitutional before an election that uses the system takes place. Courts do not rule on such controversies in advance.

For now, Cynthia Reichert, the chief Minneapolis elections administrator, and her IRV implementation team have their hands full with a host of other complexities associated with a new voting system.

No voting system certified for use in Minnesota by federal and state law accommodates ranked voting. It's being used currently in only one major American city, San Francisco. Acquiring such a system, getting it federally certified and making its use mesh with a mind-boggling array of state election statutes make for a daunting task. For instant runoff voting to succeed, Reichert's work also must be followed by another big job -- educating voters about the new way of voting.

Reichert says she's getting excellent support from Hennepin County, which owns the city's voting equipment, and Ritchie's office, where an instant runoff voting task force has been created. But to keep instant runoff voting in Minneapolis from getting bogged down in legal technicalities, Reichert expects the city to ask the 2008 Legislature and Gov. Tim Pawlenty to clear the statutory thicket that surrounds any voting system change, and give Minneapolis express permission to proceed.

When that request comes, it deserves a cooperative reception at the Capitol. Even legislators -- and a governor -- who have qualms about the whole state moving from plurality rule to majority rule should respect a decision made by two-thirds of Minneapolis voters in 2006. The city, in effect, will conduct a dry run of a system that many Minnesotans think would serve the state well. It's in the state's interest for the city's experiment to proceed in such a way that its lessons, be they positive or negative, are clear.