New Jersey took a step toward decriminalizing marijuana possession today when an Assembly panel unanimously approved a bill that would allow offenders to pay fines instead of going to jail. Under the terms of the measure, anyone arrested with fewer than 15 grams of marijuana — just under a half-ounce or slightly more than 30 joints — would be subject to a $150 fine for a first offense, a $200 fine a second time and a $500 penalty for a third and subsequent offenses.