By month's end, federal health officials will decide whether to let women buy emergency contraception without a prescription -- and if so, if the morning-after pill will be treated more like aspirin off the shelf or like cigarettes.

Regardless of how the Food and Drug Administration (search) ends the two-year saga, it isn't likely to settle the issue. States already are moving to expand access to Plan B, the pill that can prevent pregnancy if taken soon after unprotected sex, amid some competing efforts to restrict it.

And if the FDA does allow easier access, the pills probably would come with an age limit -- anyone younger than 16 would still need a prescription. So drugstores would have to "card" young customers seeking to prevent pregnancy much as they now check cigarette buyers' ages.

How is unclear. Would morning-after pills sit next to other over-the-counter drugs or condoms? Cash registers could be programmed to block purchase pending an age check. That's doable: Walgreen's, the nation's largest drugstore chain, just last month took that step to prohibit sales to minors of cold medicines containing a sometimes-abused ingredient.

Or would the contraceptive be treated like cigarettes, put behind cash registers as a reminder against teenage sales?

Or would morning-after pills be sold only "behind the counter," meaning the pharmacist still must hand them over even though no doctor's prescription is required?

Laws in seven states -- Alaska, California, Hawaii, Maine, New Hampshire, New Mexico and Washington -- already allow women to buy Plan B that way, with no age restrictions. Massachusetts is set to become the eighth this fall, as lawmakers are expected to override their governor's veto of nonprescription sales.

Whether drugstores even agree to carry nonprescription Plan B will depend largely on whether such steps are required.

"A lot of it is going to be the ease with which it can be handled in the retail store," says Mary Ann Wagner of the National Association of Chain Drug Stores.

If FDA rejects nonprescription sales nationally, the small but growing Plan B state rebellion is sure to continue. It's legal for states to allow behind-the-counter sales because states, not the federal government, regulate how pharmacists practice, explains Dr. Alastair Wood of Vanderbilt University, a well-known pharmacologist who advises the FDA.

Still, Wood says conflicting state policy over a drug long considered safe makes little sense.

Plan B contains a higher dose of the hormones in regular birth control pills. It cuts the chances of pregnancy by up to 89 percent if used within 72 hours of rape, condom failure or just forgetting routine contraception. The earlier it's taken, the more effective it is. But it can be hard to find a doctor to write a prescription in time, especially on weekends and holidays. Hence the push to allow nonprescription sales here, just as in Britain and Canada.

If a woman already is pregnant, the pills have no effect. They prevent ovulation or fertilization of an egg; they also may prevent the egg from implanting into the uterus, the medical definition of pregnancy, although recent research suggests that's not likely.

Contraceptive advocates and doctors' groups say easier access could halve the nation's 3 million annual unintended pregnancies. FDA's own scientists call the pills extremely safe, used by more than 2.4 million Americans and millions more women abroad with few side effects. FDA's independent scientific advisers overwhelmingly backed over-the-counter sales in December 2003.

But FDA rejected that move, citing concern about young teens' use of the pills without a doctor's guidance.

Maker Barr Laboratories reapplied, asking that women 16 and older be allowed to buy Plan B without a prescription while younger teens continue to get a doctor's note. When FDA missed a January deadline to decide, members of Congress refused to seat the agency's new commissioner until he pledged a new deadline -- Sept. 1.

Opponents argue that unfettered access to Plan B could increase teen sex and are pushing states to restrict prescription access, too, such as by blocking requirements that emergency rooms or pharmacies sell it.

If the drug is sold without a prescription, FDA has no way to enforce an age restriction, says Wendy Wright of the conservative Concerned Women for America. "The person who buys the drug is not necessarily the person who takes the drug," she says. "It's a ludicrous proposal."

Plan B's proponents don't like the age restriction, either, saying teens are most in need of a second chance at avoiding pregnancy -- and that there's no evidence easier access increases teen sex or makes women of any age more careless about regular contraception.

If FDA rejects even age-staggered nonprescription sales, Planned Parenthood (search) may sue, says president Karen Pearl.

"The FDA really ignored the scientific evidence," Pearl says. "This is absolutely the best way of assuring that when something does go wrong, that people have that second opportunity to prevent the unintended pregnancy."