MONTPELIER--Supporters of the law that would implement instant runoff voting for the election of the state's highest offices are disputing Vermont's attorney general, who said such a change would require a constitutional amendment.

And they got a boost Thursday from a constitutional law scholar, who told the Senate Government Operations Committee that technically the law might not violate the Vermont Constitution and might survive a challenge to the Vermont Supreme Court.

But some senators said they still believe that instant runoff voting, or IRV, is such a drastic change from the current voting system that it should go through the cumbersome process of amending the Vermont Constitution.

“My fear is we’re going to have the Supreme Court deciding who is governor or who isn’t governor,” said Sen. Ann Cummings, D-Washington, who said she supported the concept of IRV. “This is a major change and it should go through the constitutional (amendment) process.”

At issue is a bill sponsored by Sen. Susan Bartlett, D-Lamoille, and a handful of Democratic colleagues that would change election law by having IRV applied to all statewide races. Currently, the Vermont Constitution requires that races for governor, lieutenant governor and treasurer be decided by a secret vote in the Legislature if no candidate gets more than 50 percent of the votes.

Under Bartlett’s bill, voters would mark not only their first choice, but also whom they’d pick as a second choice. If no candidate in the first round of counting gets more than 50 percent, all candidates but the top two would be eliminated and election officials would look at the second choices, if any, of voters whose first choice is eliminated.

Those votes would be given to the second-choice candidate the voter indicated. If after those votes have been added to the remaining candidate’s totals, no one has topped 50 percent, the race would still be thrown into the Legislature.

Supporters claim the system will avoid the problem of having a candidate win who was opposed by a majority of voters, and eliminate the “spoiler” charge sometimes leveled at third party candidates. In November, Gov. James Douglas won with 44.9 percent of the ballots cast while Lt. Gov. Brian Dubie was victorious with 41.2 percent, but both of their Democratic challengers, Douglas Racine and Peter Shumlin, conceded rather than push the contests into the State House.

But earlier this week, Attorney General William Sorrell, a Democrat, issued an opinion that implementing IRV through a bill like Bartlett’s would require a change in the constitution. IRV proponents said Thursday that Sorrell was being “hyper-literal” in his reading of the constitution.

“With due respect to the office, it struck me as more of an advocacy piece than analytical,” Christopher Smart, a former lawyer who lives in Montpelier, told the committee.

He argued that following Sorrell’s logic, several other sentences in the same section of the constitution could be construed to bar absentee ballots, require voters to write out the names of candidates, invalidate the role of local election officials, and require lawmakers themselves to count the ballots. Smart said the runoff provisions would be executed in such a way as to not violate the requirements of the constitution. But a constitutional scholar, Professor Peter Teachout of the Vermont Law School, said that it was up to the Legislature to decide on its own whether it believed a particular bill was constitutional.

And in doing so the Legislature should consider just how big the changes were from the current system, he said.

“I agree with a lot of what Mr. Smart said,” Teachout told the panel. “But I disagree with the approach that says, ‘Pass the bill, because it’s for the Vermont Supreme Court to decide the constitutionality of issues.’”

While he acknowledged the law on its face stood a good choice of passing a constitutional challenge to the Supreme Court, he predicted there would almost certainly be one by a third-place finisher, who under current constitutional law can be considered when the Legislature decides a race but who’d be eliminated under Bartlett’s bill.

Several senators said they favored IRV over the current system, but that it should be considered as an amendment — requiring votes in two separate Legislatures and a referendum by the public — rather than as a change in law that could be undone by another General Assembly.

“If it’s going to be challenged, I’d rather see us do it the right way first,” said Sen. Jeanette White, D-Windham. “If there’s already distrust about our ability to choose a governor and lieutenant governor then certainly there’s going to be distrust about our ability to decide how to run an election.”

Jesse Rosado, a Montpelier resident and Progressive candidate for the House who works for the Voter’s Choice Coalition, a group pushing IRV, said that if an amendment wasn’t needed it shouldn’t be used, and that his group only wanted to see the bill debated by lawmakers on the floor. He said passage of advisory votes at dozens of town meetings and nearly 500 signatures on a petition demonstrated ample public support for IRV.

That didn’t impress Cummings.

“Why, unless you’re afraid you’re going to lose, do the proponents not want to do it as a constitutional amendment?” she asked. “… If we’re going to do this, I think we should do it so this system has some legitimacy.”

Committee chairman Sen. William Doyle, R-Washington, has scheduled a public hearing on March 18 on Vermont Interactive Television that will take testimony on IRV, as well as two competing constitutional amendments. One, sponsored by Sen. John Bloomer, R-Rutland, would allow a candidate who got more than 40 percent of the votes to be the winner and have the top two candidates compete in a December runoff election otherwise. Another, sponsored by Sen. Matt Dunne, D-Windsor, would give the Legislature the authority to determine the election process.

Bartlett said she wasn’t averse to having her bill converted to a constitutional amendment, or having the results of IRV be simply advisory to guide the Legislature as a way of avoiding a constitutional challenge. In fact, she said both could proceed at the same time.

“I’d really like to have something in place for the next election, because I can see us being in the same spot next time,” she said. “Why not have your cake and eat it too?”

Teachout said after the hearing that because the Vermont Supreme Court generally won’t issue opinions in advance on pending cases, it would take an election — and then a dispute of the results — to ultimately figure out whether the law was constitutional.

“Do you want to put the Vermont Supreme Court in that kind of position (where) any way the court decides it’s going to have the feel of Bush v. Gore, where there’s the perception that political considerations were part of the ruling?” he asked.