"It's in our best interests to keep people who are underage out," says Grafton Street's Patrick Lee.

"If you have to rely on underage people, you're not going to succeed anyway."

Massachusetts state law requires vendors to accept only valid in-state licenses, passports or military identification as proof of age, meaning that if an underage student purchases alcohol with an out-of-state ID, the establishment is liable. But many sellers accept out-of-state licenses at their own risk to serve the sizeable portion of their client base represented by Boston's polyglot student population.

At the Harvard Provision Co., says Connealy, "the vast majority of [customers'] IDs are from out of state."

To that end, most stores that sell alcohol pay outside experts to train their employees to catch fake IDs. They often have tools at their disposal: a book of out-of-state IDs to match up against suspicious attempts, and a scanner that allows them to verify many licenses.

"The book is really good," says Partington. "It tells you about the typesetting, and even how the material feels...[But] even a good fake looks fake."

Many establishments actually confiscate fakes that have failed to work their magic. Although, according to Connealy, "it's a gray area of the law, if there's any doubt, we'll call a police officer, and that usually settles it."