The "morning-after" contraceptive known as Plan B comes to the nation's largest retailer this week. Wal-Mart will begin stocking the prescription drug in its pharmacies across the country. The chain made the decision after the Massachusetts pharmacy board ruled it must do so in its 44 Massachusetts pharmacies.

Illinois had previously required Wal-Mart to stock the pill, which consists of a high dose of hormones that women can take three to five days after unprotected sex to prevent pregnancy.

Three Massachusetts women had sued Wal-Mart for not carrying the pill, leading to the Board of Pharmacy's decision. There had also been protests around the country by activists who labeled Wal-Mart as "anti-woman" and noted it was the only large pharmacy chain in the country that failed to carry the product.

Ever since the drug was approved by the FDA, Wal-Mart had said that "for busienss reasons" it chose not to stock the pill. But after bruising battles including a massive gender-discrimination lawsuit and criticism of its high-deductible health plan, Wal-Mart management apparently decided it did not need to give its critics any more ammunition.

However, it remains to be seen whether Plan B will actually be available at Wal-Mart pharmacies. The company says it will allow pharmacists who object to the pills for personal reasons to refuse to dispense them, sending customers elsewhere.

But since Wal-Mart has driven many rural pharmacies out of business, it is the only full-service pharmacy in many of the regions it serves. Thus, the decision to let pharmacists decide what they will and won't dispense could provoke a new round of recriminations. In some areas, consumers are also circulating petitions demanding Wal-Mart rescind the policy.

Pressure groups on the other side are also mobilizing. At least 16 states are considering legislation that would allow pharmacists to refuse to fill prescriptions for any kind of birth control.