It's a weak defense to say MJ OD'd himself, when that drug should never have been prescribed for him, nor be allowed to under his control. It's intended for anesthesiology uses in a controlled clinical setting, not left with a patient in his bedroom at home without proper equipment. And its use is not approved as a sleep aid.
There is also testimony pointing to medical incompetence, attempts at a cover-up, and lying to both the EMT first-responders and later the ER staff. Clearly this doctor should be convicted, but US juries are notoriously fickle, so who knows. It appears the defense if hoping to portray MJ as just another self-abusive entertainer who accidentally killed himself with drugs, the doctor merely an innocent bystander, rather than the unethical & incompetent enabler he really was.