In the year since it was approved for over-the-counter sales, the morning-after pill has become a huge commercial success for its manufacturer, but its popularity and solid safety record haven’t deterred critics from seeking to overturn the milestone ruling.

The pill, marketed by Barr Pharmaceuticals Inc. as Plan B, was the focus of bitter debate for three years. After repeated delays, the Food and Drug Administration declared on August 24, 2006 that customers 18 and older should be able to buy it in pharmacies without a prescription.

Barr, based in Woodcliff Lake, N.J., began distributing the over-the-counter version last November, and all national pharmacy chains now stock it. The company projects that sales of Plan B will total about $80 million for 2007, almost double the total for 2006 and up eightfold from 2004, when Barr acquired the product as a prescription-only drug.

“Overall, we’ve been very pleased with the acceptance,” a Barr spokeswoman, Carol Cox, said. “The product may not be for everyone — but if you find yourself in a position to need it, absolutely it should be available.”

Despite the booming sales, and evidence that the pill is safe if properly used, critics remain active.

A coalition of conservative groups, including the Family Research Council and Concerned Women for America, has filed a lawsuit in federal court in Washington seeking to reverse the FDA ruling. The groups contend that the FDA acted unwisely under political pressure and lacked authority to approve the same drug for both over-the-counter and prescription-only distribution based on the user’s age.

“Barr may be making a healthy profit, but women are paying the price,” the president of Concerned Women for America, Wendy Wright, said. The group believes Plan B is less effective that its backers assert.

Barr says Plan B, a high dose of a drug found in many regular birth-control pills, can lower the risk of pregnancy by up to 89% if taken within 72 hours of unprotected sex.

Since the FDA ruling, there have been extensive efforts by advocacy groups and some politicians to ensure widespread availability of Plan B.

– Several states have enacted laws to improve rape survivors’ access to the medication in hospital emergency rooms; a similar bill has been introduced in Congress.

– Also in Congress, supporters of Plan B have introduced legislation to ensure that women serving in the American military overseas have access to the pills at their bases. The measure’s backers say servicewomen and military doctors often can’t obtain the medication when it’s needed.

– Planned Parenthood, NARAL Pro-Choice America and their allies have campaigned to educate women about Plan B and pressure national pharmacy chains to make it readily available. Overall, activists are pleased with the chains’ response, but they say women continue to encounter pharmacies which refuse to stock Plan B and individual employees who, for reasons of conscience, refuse to sell it.

“Many women still don’t know it’s available,” NARAL’s president, Nancy Keenan, said. “There’s a lot of education that needs to be done.”

During three years of FDA deliberations over Plan B, many claims were made about it. Supporters said it would reduce the number of unintended pregnancies and abortions; opponents said it would fuel teenage promiscuity because girls under 18 could obtain it from an older person — male or female — buying it over-the-counter on their behalf.

Thus far, there have been several studies casting doubt on all these claims — although activists of varying views say there is a shortage of authoritative research. The president of the Planned Parenthood Federation of America, Cecile Richards, believes Plan B will contribute to a measurable drop in unintended pregnancies once accurate information about it spreads widely among American women.

“We’re talking about very mainstream health care here,” Mr. Richards said. “And yet there is a fringe group of folks in this country who seem determined to prevent women from getting emergency contraception.”

Some critics — including Roman Catholic leaders — consider the pill tantamount to abortion, although Barr says it has no effect on women who are already pregnant. Catholic bishops in Connecticut protested in May when the state legislature passed a bill requiring all hospitals, including Catholic facilities, to offer Plan B to rape victims.

The planning director for the U.S. Conference of Catholic Bishops’ Secretariat for Pro-Life Activities, Deirdre McQuade, also expressed concern about pharmacy employees, saying they should have the right to refuse to sell Plan B for reasons of conscience. Some states have passed laws to protect this right of refusal.

“Pregnancy is not a disease,” Ms. McQuade said. “There is no absolute duty to dispense a non-therapeutic drug, but there is a basic civil right of conscience.”