Marijuana laws for 18 years and older versus younger than 18 are different. Primarily if the 18 year old is found on school grounds (when the school is open or for programs) with not more than 28.5 grams they face a fine of not more than $500 and/or 6 months in the county jail. People under 18 are subject to a fine of no more than $250 for the first offense and $500 for the second or commitment to a juvenile facility for up to 10 days. The marijuana cannot be the concentrated cannabis kind.
In California, any minor under the age of 21 who is convicted of a marijuana offense faces a 12-month drivers license suspension. The offense does not have to be driving related, either. Simple possession will lead to license suspension for anyone under the age of 21 in California. This is in addition to any other fines imposed during conviction.
Any minor (age under 21) convicted of any marijuana, alcohol, or other drug offense faces a 12-month drivers license suspension, regardless of whether the offense was driving-related. The court may allow restricted license privileges if the minor demonstrates a “critical need to drive.”