You have to put in a request. It is up to the discretion of the command whether or not they will let you revoke your waiver. Get with military defense counsel ASAP. Somewhere in your notication letter it says that.
They can testify.
There may be issues about credibility, especially if there is evidence of "planting drugs."
Get a good criminal defense lawyer from that area. It's quite possible H/she knows the officer and his history if they do a lot of drug cases in town.
Go back and read the contract you signed.
It is likely you signed a contract for six years active, and two years inactive Reserves. There are some contracts for less, and for more, depending partly on what branch of the Army you are to serve in.
It looks like you have reasked your question with some more facts.
There are some more comments on your first question, look those over.
If he is still on active duty there are some things you might be able to do to help better the situation.
1. This is not something you should be discussing on an open forum like this, where people can read this.
2. If you have since been discharged, then you should be OK. The situation you read about is certainly egregious, but your case doesn't seem like that. Also, there's nothing based on what you've said that clearly establishes you should have been DQ'd.
If a SM declines Art. 15 the commander options are: court-martial, GOMR (and) commencement of elimination proceedings, or do counseling and adverse performance report ant nothing else. There are other administrative actions that might be involved - flagging, removal of security clearance.
How quickly and how effectively this works depends on rank, unit, charges, and evidence.
Sometimes if the work is lazy then there can be successful challenges to administrative actions.
When someone goes AWOL the person and their next of kin are sent a letter after 10 days, it is called the "Ten Day Letter." That says the person is AWOL, will be classified as a deserter, and that the person should be encouraged to return voluntarily. It does not advise that under federal law aiding a deserter is a federal crime.
After 30 days a DD Form 553 (Deserter arrest warrant) is issued and sent to the NCIC database so that law enforcement has access to that information. Most often a...
Yes, he needs to get legal counsel.
At his likely rank and years of service this is a significant event that may prevent him remaining in the military, getting promoted, or other adverse career effects.
Yes, it is not a conviction but it remains in the records and it may affect the quality of his discharge.