A minor in possession (MIP) is a criminal offense that is created when someone under the legal drinking age is in possession of alcohol. This is separate from the act of the minor being drunk—the mere act of holding the alcohol or having it in a vehicle with them can give rise to a charge of minor in possession.
Any time someone under the legal drinking age is caught drinking and around alcohol, such as at a party where alcohol is present, they are charged with this offense.
There is a monetary fine for minor in possession, commonly referred to as an MIP. The person who gains the MIP can be forced to attend alcohol rehabilitation classes or any other court-appointed classes that the court deems appropriate. Community service is also a common result of an MIP ticket.
Most of the time, the minor in question will have to tell law enforcement officers where they obtained the alcohol, and if it was from a person over the age of 21 (if so, then charges will be brought against that person as well).