The ruling by U.S. District Judge David C. Bury means the new restrictions will take effect Tuesday.
The rules ban pill-induced abortions after seven weeks of pregnancy, compared with the current nine-week restriction.
Bury made his ruling in response to a lawsuit by Planned Parenthood Arizona and the private abortion clinic Tucson Women's Center, who say the rules severely infringe on a woman's ability to have an abortion. He was asked to grant an injunction that would have blocked the rules from taking effect.
The rules were released in January by the Arizona Department of Health Services. They ban women from taking the most common abortion-inducing drug RU-486 after the seventh week of pregnancy. Existing rules allow women to take the abortion pill through nine weeks of pregnancy.
Planned Parenthood estimates that 800 women would have had to get surgical abortions in 2012 if the rules were in effect then. An attorney for the organization also told the judge last week that the new rules could force its Flagstaff abortion clinic to suspend operations because it does not offer surgical abortions. But a spokeswoman said Monday that the organization is still evaluating how it will proceed and operations at the Flagstaff clinic will continue.
In his ruling, the judge acknowledged that the new rules will make it more difficult for some women in Arizona, especially those in the northern part of the state, to get abortions as they have to travel farther and make more trips to clinics. But he said they aren't obstacles big enough to show that the rules should be blocked.
"The court finds that the injunction is not in the public interest," he said.
Attorney Mike Tyron, arguing the case for the state, described the rules as a simple shift in abortion regulations that amount to a minor inconvenience for women and are not the heavy-handed change that opponents make them out to be.
The Arizona Legislature in the past few years has approved a number of aggressive anti-abortion measures. A House of Representatives-approved bill that is being considered by the Senate would allow for surprise, warrantless inspections of abortion clinics. Proponents of the bill say it protects women from clinics that are not up to health standards. Opponents say it puts women at risk and violates their privacy.
The Arizona rules limit RU-486 to use under the Food and Drug Administration drug label approved in 2000, which uses a much higher dosage. That dosage is no longer routinely followed because doctors have found much lower dosages are just as effective when combined with a second drug.
The rules require that the drug be administered only at the FDA-approved dosage no later than seven weeks into a pregnancy instead of nine weeks, and that both doses be taken at the clinic. The usual dose is lower and now usually taken at home, decreasing the cost and chance of complications.
Ohio and Texas have similar laws requiring the use of only FDA-approved protocols for drug-abortions that have been upheld by federal courts, although those states have exemptions for women whose life is endangered, who have severe health problems or for whom surgical abortion would not be appropriate. Arizona's law doesn't allow for exemptions, making them the most stringent in the country. State courts in Oklahoma and North Dakota have blocked similar rules.
The Center for Arizona Policy, a powerful anti-abortion group that pushed the 2012 law, has pushed a series of anti-abortion bills. Two of those, a ban on Medicaid money for any of Planned Parenthood nonabortion services and a ban on abortion after 20 weeks, have been blocked by federal courts.
"When Planned Parenthood loses, women win," said Cathi Herrod, president of the Center for Arizona Policy. "It's common-sense regulations protecting the health and safety of women considering an abortion."
The Center for Reproductive Rights, which filed the lawsuit on behalf of Planned Parenthood, says it will continue to challenge the rules in court.
"This law serves no purpose other than to prevent Arizona women from using a safe alternative to surgical abortion and force their doctors to follow and outdated, riskier, and less effective method. This is what happens when politicians, not doctors, practice medicine," said attorney David Brown.