"We are reviewing the decision and evaluating the government's options," said F. Franklin Amanat, a lawyer for the government.
It's the latest twist in a decadelong push for easier access to emergency contraception, which can prevent pregnancy if taken soon enough after unprotected sex.
The Food and Drug Administration actually was preparing to lift all age limits on Plan B One-Step in late 2011 when Health and Human Services Secretary Kathleen Sebelius, in an unprecedented move, overruled her own scientists. Sebelius said some girls as young as 11 are physically capable of bearing children but shouldn't be able to buy the pregnancy-preventing pill on their own. President Barack Obama said he supported the decision, also citing concern for young girls.
That move shocked women's groups and in his ruling, Korman blasted Sebelius for what he called an "obviously political" decision.
"This case is not about the potential misuse of Plan B by 11-year-olds," Korman wrote, saying the number of young girls using such drugs "is likely to be minuscule."
Yet the sales restrictions are making it hard for women of all ages to buy the pills, especially young and low-income ones, he said.
In Utah, Planned Parenthood sold 26,000 cycles of the drug last year, said Karri Galloway, the agency's director. That number is lower than in the years before the prescription requirement was lifted for women aged 17 and older, she said.
"The main issue for us is contraception," she said. "One woman who needs it and is prevented from getting it when she needs it because it is a time-sensitive medication is one too many."
Data show about half of the pregnancies in Utah are unintended, said Galloway, who knows of no health-related problems that have occurred from the use of the drug in women of any age.
"The research over and over again says that women of any age can take it safely," she said.
Korman noted that numerous over-the-counter drugs are dangerous for children, but are sold nevertheless without age requirements, while "these emergency contraceptives would be among the safest drugs sold over the counter."
"It has been clear for a long time that the medical and scientific community think this should be fully over the counter and is safe for women of all ages to use," said Susan Wood, who resigned as FDA's women's health chief in 2005 to protest Bush administration foot-dragging over Plan B.
"Having worked on this for many years, the judge really wanted to make it clear that FDA had come to a scientific determination and was once again overruled, and that is not acceptable," she added.
Social conservatives criticized the ruling.
"This ruling places the health of young girls at risk," said Anna Higgins of the Family Research Council. "There is a real danger that Plan B may be given to young girls, under coercion or without their consent. The involvement of parents and medical professionals act as a safeguard for these young girls. However, today's ruling removes these commonsense protections."
Salt Lake Tribune reporter Jennifer Dobner contributed to this report.
Timeline of decisions on morning-after pill
A federal judge has ruled there should be no age restrictions on sales of the morning-after pill, in the latest development in the decade-long push for easier access to emergency contraception.
A timeline of decisions on the pills, now sold as Plan B One-Step:
1999 • The Food and Drug Administration approves prescription sales of Plan B.
2006 • The FDA approves non-prescription sales for women 18 and older. Younger women would need a doctor's prescription. Because of the age limit, the contraception is behind pharmacy counters, so consumers have to ask for it rather than picking it up off the shelves.
2009 • U.S. District Judge Edward Korman in New York orders the FDA to lower the age restrictions to 17.
2011 • Health and Human Services Secretary Kathleen Sebelius overrules FDA's plan to lift age restrictions on nonprescription sales of the morning-after pill. She says young girls shouldn't be able to buy emergency contraception on their own.
2012 • Korman rules that the age restrictions on over-the-counter sales of the morning-after pill are "arbitrary, capricious and unreasonable" and must end within 30 days.