JACKSON — Mississippians are voting Tuesday on three ballot initiatives that propose to amend the state constitution.

Initiative 26, also known as the “personhood” initiative, would declare that life begins at fertilization.

Initiative 27 would require voters to show government-issued identification at the polls.

Initiative 31 would ban the government from using eminent domain to take land for private economic projects.

State law says that for any initiative to pass, it needs a simple majority, and it must receive at least 40 percent of the total votes cast in the election. That means an initiative might be in jeopardy if it receives significantly fewer votes than are cast in top-of-the ballot races such as the governor’s election. Initiatives are expected to be at the bottom of the ballot in most counties.

State law says any initiative that passes would take effect 30 days later. But there could be court challenges for any of the three amendments, if voters pass them.

Mississippians have voted on only two previous ballot initiatives, defeating both. One on the November 1995 ballot would have limited terms of state and federal elected officials. One on the November 1999 ballot would’ve limited the terms of state legislators.

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Initiative 26, backed by the Colorado-based Personhood USA, seeks to provoke a court challenge to Roe v. Wade, the 1973 U.S. Supreme Court ruling that established a legal right to abortion. Mississippi is the only state voting on a life-at-fertilization amendment this fall.

Supporters say the initiative seeks to end abortion in a state that already has some of the nation’s toughest abortion regulations and only one clinic where the procedures are performed.

Opponents say defining life as beginning at fertilization could block common forms of birth control and deter physicians from performing in-vitro fertilization.

Atlee Breland of Brandon, who’s active in the Parents Against Mississippi 26 group, said she has three children because of in-vitro fertilization. She said she believes the initiative could drive IVF specialists out of the state.

“This should not just be a matter of concern for women, but for every Mississippi family,” Breland said. “Everybody knows somebody that has gone through infertility. Everybody knows somebody who has had life-threatening pregnancy issues.”

Anne Reed of Tupelo, who’s active in the Yes on 26 group, describes herself as a “post-abortive mother,” and said she provides counseling for other women who have had abortions.

“With every woman that I have counseled that is post-abortive, there are consistent feelings of that experience, of actually being in that clinic, of feeling devalued, dehumanized,” Reed said.

The Mississippi State Medical Association says it is not supporting the ballot measure — a step short of actively opposing it. The Mississippi section of the American College of Obstetricians and Gynecologists opposes the initiative. Some OB-GYNs, however, support the proposal.

Glenn Cohen, a Harvard Law School professor, said Initiative 26 is “ambiguous.” He said if it passes, judges will have to interpret it and determine how it applies to Mississippi law and whether, for example, it would affect birth control, IVF or only abortion.

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Mississippi lawmakers argued about voter ID for more than 15 years before Republican Sen. Joey Fillingane of Sumrall started the petition drive that put Initiative 27 on the ballot. Supporters say requiring ID would protect the integrity of elections. Opponents say there’s been little proof that people are trying to vote under others’ names, and that requiring ID might be a way to intimidate older black voters who were once subject to Jim Crow laws.

The National Conference of State Legislatures says 30 states require all voters to show ID at the polls, many of them in the Deep South. Fourteen of the 30 require photo ID.

Nsombi Lambright, executive director of the American Civil Liberties Union of Mississippi, said that in poor, rural areas, many people might lack any form of government-issued photo ID. She also worries a voter ID law would be applied unevenly, and perhaps unfairly, by poll workers who might not be well trained.

Secretary of State Delbert Hosemann, a Republican who is Mississippi’s top elections official, said he supports the voter ID ballot initiative.

“We in Mississippi need to step away from where we were 50 years ago. We’ve made a great deal of progress,” Hosemann said. “A commonsense voter ID to enforce the integrity of the voting for every Mississippian makes sense.”

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Eminent domain is the process government uses to take private land for projects ranging from road construction to industrial development. Initiative 31 would not stop eminent domain for public uses such as road and bridge construction or placement of utility lines. It proposes banning state and local governments from taking private property and, within 10 years, giving it to other private citizens or businesses.

The U.S. Supreme Court ruled in a Connecticut case in 2005 that land could be taken for private development. Since then, more than 40 states have enacted restrictions on eminent domain for private projects.

Mississippi Gov. Haley Barbour in 2009 vetoed a bill that would’ve restricted eminent domain. The Republican argued that the restrictions would hurt the state’s pursuit of big projects such as automobile manufacturing plants.