Georgia Gov. Brian Kemp signed one of the strictest abortion laws in the country Tuesday, setting the state up for what is likely to be a lengthy — and costly — court battle.

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More than a month after the Georgia General Assembly approved the legislation, Kemp, in a Capitol ceremony, signed House Bill 481, outlawing most abortions once a doctor can detect a fetus' heartbeat — usually around six weeks of pregnancy and before most women know they're pregnant.

In signing the bill, Kemp made good on a promise made during his 2018 campaign to sign the strictest abortion laws in the country.

>> Georgia state House passes controversial 'heartbeat' abortion bill

“All life has value, all life matters and all life is worthy of protection,” Kemp said. “I’m signing this bill to ensure all Georgians have the opportunity to live, grow, learn and prosper in the great state of Georgia.”

The law is scheduled to go into effect in January unless it is blocked by the courts. The American Civil Liberties Union of Georgia has vowed to sue the state over the new law.

“This bill has big government criminalizing the most intimate decision women and couples make and flies in the face of 50 years of U.S. Supreme Court precedent,” said ACLU of Georgia Executive Director Andrea Young. “We will see Governor Kemp in court.”

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Georgia's law is one of several moving through state governments with the express purpose of challenging the 1973 U.S. Supreme Court's Roe v. Wade decision that guaranteed a woman's right to an abortion until a fetus is "viable" — up until about 24 weeks of pregnancy. Georgia passed legislation in 2012 that banned abortions after 20 weeks.

Governors in Kentucky, Mississippi and Ohio all have signed similar “heartbeat bills.” A federal judge has already issued a preliminary injunction against the Kentucky law, and similar laws enacted in recent years in Iowa and North Dakota have also been struck down in the courts.

>> On AJC.com: Could Georgia abortion law challenge Roe v. Wade?

Other than using the detection of a “heartbeat” as the cutoff, each state has taken a slightly different approach to its law.

In Georgia, later abortions still are allowed in cases of rape, incest, if the life of the mother is in danger or in instances of "medical futility," when a fetus would not be able to survive after birth. To obtain an abortion after six weeks because of rape or incest, a woman would have to file a police report.

>> On AJC.com: A look at abortion bills around the U.S. in 2019

The anti-abortion organization Save the 1 said allowing exceptions to the abortion ban was discriminatory because it valued certain fetuses over others. The group vowed to sue the state.

The Georgia law also includes what many supporters call “personhood” language, which would extend legal rights to fertilized eggs.

Georgia’s law allows parents, once a heartbeat is detected, to claim an embryo on their taxes as a dependent, and it would be counted toward the state’s population. A court can also order a father to pay child support after a heartbeat is detected.

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The law also exposes the mother to criminal prosecution, as well as the doctor who performs the abortion, the nurse who assists in one and any pharmacist who prescribes medication that terminates a pregnancy. It grants exceptions to situations where the health or livelihood of the mother is at stake and for “the accidental or unintentional injury to or death of an unborn child.”

What defines a heartbeat is at the center of dispute.

>> On AJC.com: ‘We warned you.’ Abortion rights groups vow payback as Kemp preps to sign ‘heartbeat’ bill

Supporters say it should be used to establish when life begins.

“If you look at a child in the womb with a beating heart and a distinct blood type and you ask a school child what that is, they know,” said Rep. Ed Setlzer, R-Acworth, the bill’s sponsor. “They say, ‘That’s a baby.”

Doctors who oppose the law, however, said what appears to be a heartbeat at six weeks signals the practice motions of developing tissues that could not on their own power a fetus without the mother.

There are already about 20 lawsuits involving abortion that the U.S. Supreme Court could consider that would challenge Roe v. Wade, but supporters of the new law said they believe Georgia’s ban is the one that will overturn the landmark ruling.

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Still, defending the state’s law is going to be costly.

For example, Louisiana spent more than $1 million on private attorneys defending a 2014 anti-abortion law that attempts to require doctors who perform the procedure to have admitting rights at a nearby hospital.

That amount could balloon quickly after a federal judge ruled in 2017 that requiring admitting privileges was unconstitutional. Lawyers for a clinic that performs abortions have asked for $4.7 million to pay for legal fees. Louisiana is appealing the 2017 ruling.