Disclosed are bag check machines, including related methods, apparatus, and systems, including computer program products, implementing and using techniques for allowing a user to self-check one or more items for transportation. The user is first enrolled in a self-check program by reading personal ID information from a government-issued identification (ID) document and verifying the ID document based on the personal ID information. Biometric data from the user is captured and stored, in an encoded form, on a portable ID storage medium issued to the user. For the user to self-check one or more items, encoded biometric data is read from the portable ID storage medium, and biometric data is captured from the user. When the captured biometric data matches the biometric data read from the portable ID storage medium, the user is authorized to check-in the item or items.