PROVIDENCE, R.I. — Rhode Island voters will decide in November whether to give an ethics commission power to investigate lawmakers for conflicts of interest and sanction them when they are found to have acted improperly.

The Rhode Island Ethics Commission once had oversight over state lawmakers, but lost it in a 2009 court ruling. The ethics ballot measure, Question 2, asks voters to approve a constitutional amendment restoring the commission’s oversight.

Good-government groups that back the measure say it will deter unethical behavior and force lawmakers to disclose potential conflicts.

“There are endless examples of when people have the opportunity and no possibility of being prosecuted, at least some will do unethical things,” said H. Philip West Jr., who led Common Cause Rhode Island from 1988 to 2006 and wrote a book about the fight to reform the state’s scandal-prone government.

“Some people will be honest no matter what the temptation is,” West said. “Some people will be dishonest no matter the enforcement mechanism. And there are a bunch of people who could go either way, depending on whether they think they’ll get caught.”

The proposed amendment has no organized opposition, but some critics have said that it raises free speech concerns and that complaint-driven ethics investigations could be used for retribution. They include the Republican minority leader in the House of Representatives, a teachers’ union leader and the state chapter of the American Civil Liberties Union. The ACLU said it gives an unelected agency too much authority to decide what legislators can debate and vote on.

Other Republicans support it, including West Warwick Rep. Patricia Morgan, the House’s deputy minority leader, who has sought to curtail abuse of legislative grants that politicians award to favored organizations.

“We’ve had oversight in the past, and we’ve caught some bad guys through it,” Morgan said. “The Ethics Commission oversight needs to be restored.”

Voters approved the forming of an ethics commission in 1986. At the time, it was considered among the strongest in existence, West said. But it lost much of its power in 2009 when a lawmaker challenged it in court after being investigated for allegedly pushing legislation that favored his business associate.

After years of delay, recent scandals helped compel top lawmakers to push to restore the commission’s power this year. Both chambers of the General Assembly unanimously passed legislation that put the question on the Nov. 8 ballot. Some lawmakers had been concerned about frivolous, politically motivated complaints prompting investigations, so the ethics board in July created a blackout period to ban public complaints from being submitted in the 90 days before an election.

“Of course, any process that allows public complaint can be abused in some fashion,” said John Marion, the current director of Common Cause Rhode Island. “We’ve taken steps to deal with frivolous complaints, but that’s not an excuse for not restoring the (commission’s) jurisdiction” over lawmakers.