It is unclear from your question whether the charge is simple possession or possession with I tent to deliver. It will also be important to know if be has a prior record. In any event, an experienced criminal defense attorney must be secured to pursue all defenses and resolve the case in an appropriate manner.
There is not nearly enough information here to answer the question. By "possession" are we talking about simple possession, a misdemeanor or possession with intent to deliver, a felony under the Drug Act? The amount by weight is extremely important for sentencing purposes and whether your son is a juvenile or an adult is likewise. In any event, please do not post anymore details on this public website or anywhere else on the Internet, including social media like Facebook. Your son needs the assistance of qualified criminal defense counsel without delay. Most of us here, myself included, offer free consultations. Take advantage of that opportunity to discuss this situation privately and confidentially with one or more lawyers experienced in drug defense. Good luck.
If it is simple possession, not very likely but it could still have a destructive impact on your future if not handled properly. If it was possession with the intent to deliver, the chances of jail time goes up dramatically.
Michael L. Doyle
This is not intended as individual legal advice and there is no attorney client relationship established by this answer. It is advisable that you seek individualized legal assistance. This is not a substitute for hiring an attorney.