When Maine voters cast ballots Tuesday on referendum Questions 1 and 2, it will be the 30th and 31st time that’s happened over the last two decades.

Since 2004, the state has passed 14 citizen-led ballot initiatives that have established laws for medical marijuana and later legalized recreational cannabis, expanded Medicaid, and allowed same-sex couples to marry.

Fifteen have failed, including several efforts to reduce taxes, several that tried to establish casinos in different parts of the state, and a proposed tax on wealthy households to pay for universal home health care for seniors and disabled residents.

Roughly half of all U.S. states have some form of citizen initiative, although Massachusetts is the only other in New England. Some states, such as California, have considered citizen initiatives at a higher frequency.

Maine’s process has been in existence for over 100 years, and recently there have been several statewide initiatives on the ballot, notably 4 in 2023 and 5 in 2016. But there weren’t any in 2019, 2020 or 2022.

“The idea is to give regular citizens more of a voice in the policy process,” said Dan Shea, a professor of government at Colby College, who said Maine’s process originated at a time when corrupt party machines often controlled legislative efforts at the turn of the 20th century.

“The process was designed to allow citizens to step beyond leaders of the parties in the Legislature and get stuff done,” he said.

There are some downsides to passing legislation by referendum. Citizens’ initiatives can draw out-of-state influence and money, especially from activists who may see Maine’s relatively low media costs as an invitation to test policies here, and the proposals are often complex, meaning it can be a challenge for voters to fully grasp all the details and impacts.

“Maine is a pretty cheap state for advertising,” said Michael Franz, a professor of government and legal studies at Bowdoin College. “And because Mainers see it as part of their political culture to vote on these measures, it becomes a perfect place for advocates of different measures and ideas to put them on the ballot and test them in the state.”

“Also, given the political polarization today and the frustration many people have with elected officials, it’s an opportunity for people who have an idea and want to get things in front of people to just bypass elected officials entirely,” he added.

Franz said many Maine voters are wary of out-of-state influence and that while the proposals can be complex, the electorate as a whole has shown to be “pretty savvy” when deciding on citizens’ initiatives.

Not having gone through the normal legislative process though, many of the measures also end up being the subject of legal challenges.

To qualify for the ballot in Maine, supporters need to gather enough signatures – equal to 10% of the turnout for the most recent gubernatorial election. This year that was 67,682 signatures. It’s a high enough threshold, political scientists say, to prevent the process from being overused or abused.

Citizen-led initiatives have often been used to push for laws that the Legislature is unwilling to take up or support. Some people may see them as an opportunity for lawmakers to “pass the buck” and avoid making decisions on controversial measures themselves, Shea said, though they’ve also put Maine on the leading edge of some issues nationally.

Here’s a look at 10 high-profile citizen-led initiatives that have passed or failed in recent years.

Staff writer Rachel Ohm contributed to this report.