The Cambridge Police Department says it is about to crack down on local stores that sell alcohol to minors, with officers using youths as decoys to check whether cashiers ask for identification.

Cashiers who fail to comply will be required to attend a disciplinary hearing with the Cambridge License Commission, a police spokesman said in a telephone interview yesterday. The operation, set to run this month in coordination with Mothers Against Drunk Driving (MADD), was reported on a Cambridge Chronicle blog this week.

The announcement comes as the College mounts its own crackdown on underage drinking. And it comes three years after the old owner of Louie’s Superette, the popular convenience store near Mather House, had his license suspended for 12 days for selling alcohol to minors.

While it is illegal for stores to sell alcohol to youth, there is no state law that specifies when employees must ask for identification. That decision varies from store to store and from person to person.

The Z Square cafe on JFK Street requires its employees to read a handbook on when to card and how to spot fake IDs, according to employee Mike Jones. He said workers there were required to ask anyone who looks younger than 30 for identification—and two forms of it if the customer doesn’t show a Mass. identification card or a U.S. passport.

The call on whether to card can also depend on a person’s purchase.

“I do it by looks, but it also depends on what they’re buying,” said Cardullo’s cashier Francesca A. Vitale. “A person who is buying an expensive bottle of wine, instead of vodka, is less likely to be underage.”

But according to a cursory survey of Square establishments, the most stringent might be an undergraduate favorite—the Hong Kong restaurant.

“We ask 99 percent of our clientele for an appropriate form of identification,” said David T. Hayes, a manager at the Kong.

Under state law, providing a minor with alcohol can be punished with a fine or even jail time. But, as was the case with Louie’s Superette, the consequences are rarely that harsh. Generally, an offending establishment may get a warning letter or be forced to close for up to three days, said Amy Whitney, the Massachusetts youth program coordinator of MADD, a group that works with community law enforcement agencies to enforce underage drinking laws.

About 20 percent of stores across the country sell alcohol to minors, said Barbara B. Harrington, the state executive director for MADD. “There is this myth that youth only get alcohol through the use of fake IDs,” she said.

The Cambridge police will draw from a group of youth volunteers organized by the city’s license commission, said the police spokesman, who did not give his name. Elizabeth Lint, the commission’s executive officer, said that group had yet to be assembled.