For many 21-year-olds in Massachusetts, the phrase "Are you legal?" may soon be a sticky question again.

Under a recently-passed state lave, even legal adults can only but alcohol with a Massachusetts driver license or Massachusetts state ID.

Although the law does not go in to effect until Oct. 1, establishments selling alcohol, including bars, liquor stores and convenience stores, are already required to display the warning.

Some local businesses, however, may not enforce the policy too strictly.

"I put [the sign] up to encourage people to complain," said Rick Sarvas, a Lil' Peach checker who works night shifts.

"We're going to continue business as usual until we find out if we'll be fined for accepting a real New York ID," Sarvas said. "If we stick with [the policy], we will lose business."

The issue is an important one for Harvard Square stores. On weekends, Serves said, students buy about three fourths of the alcohol he sells.

Others, however, said they are committed to abiding by the rules, even if it hurts sales.

"It doesn't make any sense," said Victor M. Chavez, manager at Cardullo's. "But we have to follow the law."

Chavez said Cardullo's receives a substantial portion of its business from out-of-state tourists.

"We already have people upset, Chavez said. "It'll hurt our business because we get people from all over the world."

Chavez said he believes that a possible reason for the passage of the law is the state's desire to increase revenge from the sale of Massachusetts state IDs.

But, he added, the state's money loss from lower alcohol sales will be greater than the profit from the new law.

"They may make money off of the licenses, but overall they'll lose money," Chavez said.

Businesses are not the only ones complaining.