As of last November, changes in Immigration Law in Mexico have created new requirements for minors (ages 17 and under) travelling to and from Mexico without their parents or legal guardian. The minors must submit their immigration documents, as well as a notarized letter from the parent permitting the child to travel without them. This letter must be certified with an apostille stamp and be translated into Spanish.
Failing to comply with these regulations can lead to the passenger(s) being prohibited from boarding and/or a fine.