Republican Gov. Jan Brewer signed the measure into law in April, making Arizona one of 10 states to enact types of 20-week bans.
Arizona's ban, set to take effect Thursday, prohibits abortions starting at 20 weeks of pregnancy except in medical emergencies. That is a change from the state's current ban at viability, which is the ability to survive outside the womb and which generally is considered to be about 24 weeks. A normal pregnancy lasts about 40 weeks.
The New York-based Center for Reproductive Rights said it and another group that challenged the law plan to file an emergency appeal of Monday's decision with the U.S. Court of Appeals for the Ninth Circuit.
"Today's decision casts aside decades of legal precedent, ignoring constitutional protections for reproductive rights that have been upheld by the United States Supreme Court for nearly 40 years and threatening women's health and lives," said Nancy Northup, the center's president and chief executive.
Teilborg held a hearing Wednesday on a request from abortion-rights groups that he temporarily block the law's enforcement.
The abortion-rights groups' lawyer said during the hearing that the ban crosses a clear line on what U.S. Supreme Court rulings permit, and it intrudes on women's health decisions at a key point in pregnancy. Maricopa County Attorney Bill Montgomery said the state legislature was justified in enacting the ban to protect the health of women and shield fetuses from pain.
A second Arizona antiabortion law enacted this year also faces a court challenge. That law would bar public funding for non-abortion health care provided by abortion doctors and clinics. Both laws are among many approved by Arizona's Republican-led legislature. The other laws include restrictions on clinic operations, mandates for specific disclosures, and a prohibition on a type of late-term abortion.
Attorney Janet Crepps of the Center for Reproductive Rights argued at Wednesday's hearing that under Supreme Court decisions starting with the 1973 Roe v. Wade ruling that legalized abortion, states can regulate only how abortions are performed, not ban them, before a fetus is viable.