Checking Identification and Preventing Sales to Minors
The single most effective protection against a sale to a minor is a consistent ID check. Accept only a valid, unexpired government-issued photo ID: a state driver's license or ID card, a U.S. passport or passport card, or a military ID. Expired IDs, photocopies, foreign IDs you cannot verify, and workplace badges are not acceptable. Under Alaska law a licensee or employee may be protected from certain minor-sale liability when the minor presented an apparently valid ID and the seller acted in good faith - but that defense depends on a real check, not a glance.
Use a repeatable procedure. Hold the ID in your hand, not the customer's. Check the photo against the face, check the date of birth by calculating the age rather than eyeballing the year, check expiration, and check for tampering (bubbled laminate, mismatched fonts, altered birth year, raised or peeling edges). Compare the physical description. If anything is off, ask for a second ID.
Traps in questions: assuming a person is old enough because they look it; accepting an ID because the customer is a regular; failing to recalculate the birth year around the customer's birthday; and thinking a vertical (under-21 style) license is automatically invalid - orientation alone does not prove age. Another trap is believing you must serve someone who presents any ID at all.
Worked example: today is March 14. A license shows a date of birth of March 20, four years before the customer turns 21 this year. The customer is still 20 until the 20th, so the sale is refused today. Rule of thumb: if you have to think about it, don't serve.