Under New York law, you are only eligible once in your lifetime for a marijuana ACD.
ACD stands for an Adjournment in Contemplation of Dismissal. This is offered to people that are arrested or charged in a summons or desk appearance ticket (DAT) with possession or even in some circumstances with low level sale of marijuana.
An ACD is Not a plea of guilty. You do not get a criminal record as a result of accepting an ACD.
After you are granted a marijuana ACD by the judge, your case is normally administratively adjourned (postponed) for 1 year. After the one year has passed your charges are dismissed and sealed.