If the Leader had knowledge that you were incapacitated then it would not be proper to counsel you. The proper time to inform the Leader was while you were on the phone.
Next if you were on Convalescent Leave this is an order from a doctor that is approved by the commander. Violating your con leave if not specifically directed by the commander is a possible violation of a medical order. The piece of information here is did the Leader obtain permission from the unit commander to call you in off of Convalescent Leave
While I am not an attorney I would suspect that signing a document with potential consequences while on prescribed medication is not legal as you cannot reasonably be held accountable for your actions or understanding. The fact that the counseling continued once you stated you were “high” is alarming. If you were driving and the LT allowed you to drive after this event it is a significant issue.