After two years of delays, the Food and Drug Administration's decision to yield to a court ruling and make an emergency contraceptive available over the counter to girls and women 17 and older is a triumph of science over politics.

Medical experts, including the FDA's own reviewers, originally recommended that the drug, referred to as Plan B, be made available without age limitations. But, under former President Bush, the FDA bowed to political pressure from powerful conservatives who unreasonably contend that it will increase promiscuity and erode parental rights. Some claim the drug is abortive, not contraceptive, but scientists dispute that.

At first, the drug was approved for use only with a doctor's prescription. Then the FDA gave the OK to make it nonprescription, but only to women 18 and older. A federal judge earlier this year ordered the FDA to approve the drug without a prescription for 17-year-olds, too. We believe the drug should be available over the counter to younger girls, at least to age 16, or, even better, without age restrictions.

Clearly, the usefulness of Plan B is undermined by requiring a prescription. It is highly effective in preventing ovulation or fertilization, but only if taken within 72 hours after intercourse.

The need to prevent pregnancy resulting from unwanted or unplanned sex doesn't have age restrictions. It's doubtful that teens would become sexually active or have unprotected sex more often simply because of the availability of the Plan B drug. The cost of the treatment -- $35 to $60 -- alone would put it out of reach for many teens as a regular or frequent means of contraception.

But it could be a godsend in cases of rape, including the growing problem of date rape, or when a young couple are unprepared with condoms but have sex anyway. The American Medical Association has said that ready access to emergency contraception could prevent as many as 1.7 million unintended pregnancies and 800,000 abortions each year. A mother faced with a sobbing 15- or 16-year-old daughter who is terrified of becoming a mother at that age would surely bless an FDA rule making Plan B more available.

But comprehensive sex education -- Plan A -- should be the first line of defense.

Youngsters need to understand their sexual urges, how to control them and what to do in case they decide to have intercourse despite encouragement to wait until marriage.

Sex education that includes instruction about contraception could help make Plan B -- and abortion -- less necessary.