In his article, "Jury Selection and the Unwitting Possession Defense," defense lawyer, Jamie Spencer, makes the excellent point that the prosecution must prove beyond a reasonable doubt an accused person "knew" he was in possession of contraband before the state can obtain a conviction. He presents an effective hypothetical example for use during jury selection to help prospective jurors to understand how easily a person might "unwittingly" be in care, custody, control, or management over something illegal like marijuana, a controlled substance, or maybe a weapon.
But what about "strict liability" possession cases like minor in possession of alcohol? The Texas Alcoholic Beverage Code (sec. 106.05) prohibits a person under 21 years of age from possessing alcohol. But the statute does not require a culpable mental state. In other words, the statute allows conviction even if the minor did not "know" there was alcohol in his car at the time the police found it. Case law research suggests the Texas statute, in fact, proscribes the possession of alcohol by a minor without any regard to fault.
The moral of this story? If you are a minor, watch very carefully who is getting into your car, and who's car you are getting into, during a night on the town. Police officers won't hesitate to arrest you and everyone else in the car if a can of beer is found in the front seat cup holder during a routine traffic stop.