A citizens group said Tuesday that it will sue if the St. Paul City Council tries to stop a ballot initiative that could change the way council members are elected.

A recently certified petition signed by more than 5,300 people would put a question on the November ballot asking St. Paul voters whether they want instant-runoff voting, a system approved by Minneapolis voters in 2006.

But the St. Paul city attorney's office has said the council doesn't have to put the question on the November ballot because changing the city's voting system would more than likely violate the state's Constitution.

More than likely, however, is not a good enough reason to deny the petition, said Jay Benanav, former council member and attorney for the Better Ballot Campaign. The council could only refuse to put the question to the voters if the question were "manifestly unconstitutional," meaning that it clearly violates the Constitution, Benanav said.

Instant-runoff voting, which requires voters to rank candidates in order of preference, hasn't been deemed unconstitutional, so there's no reason for the council to stop voters from deciding whether they want it in St. Paul, he said.

"Otherwise, it defeats the purpose of petitioning," said John Hottinger, a former state senator who is working with Benanav.

City Attorney John Choi, who issued a 10-page opinion on the matter last week, disagrees.

"With all due respect to the proponents of IRV, this exact argument has already been litigated at the Court of Appeals, and the appellate court flatly rejected this same argument," he said. He cited a 2005 case in which Minneapolis refused to put an amendment legalizing marijuana on the ballot.

"It's our opinion there's a strong precedent about what manifestly unconstitutional means," he said. Choi was asked by the council to give his opinion; council members can ignore it if they choose.

The council will probably vote on at least one resolution related to instant-runoff voting July 2, said Council President Kathy Lantry. She said she recognizes the right of the people to vote, but she also gives some weight to the city attorney's opinion.

"I think it would be irresponsible not to take it into consideration," Lantry said.

Better Ballot officials submitted 7,168 names a few weeks ago. The total number of verified signatures was 5,386 -- 5,098 were needed.

"You can't take lightly that over 5,000 St. Paul residents signed a petition, but you also can't take lightly the opinion of the city attorney," said Council Member Melvin Carter.

In instant-runoff voting, also called ranked-choice voting, if no candidate gains a majority, the candidate with the least amount of support is dropped and the second-place votes cast by supporters of that candidate are added to the remaining candidates. The process continues until one candidate gains a majority.

Minneapolis voters adopted the system in 2006, but it's not in place yet. A lawsuit filed by the Minnesota Voters Alliance, an opposition group, is pending.

A 1915 state Supreme Court case said a voting system in Duluth that ranked voters' choices was unconstitutional. Instant-runoff supporters say their method is different from the Duluth version and shouldn't be considered in the same way.

Choi's opinion said the method wasn't the point. Any alternative voting system would be unconstitutional, he said, because a constitutional amendment would be required for the change.

Chris Havens • 651-298-1542