Michael Jackson -- Drug Addict On Trial

Michael Jackson's intense and decades-long addiction to powerful prescription drugs will be front and center in his family's wrongful death trial ... which kicks off today.

Katherine Jackson and Michael's 3 kids are suing AEG Live, claiming the company negligently hired and supervised Dr. Conrad Murray ... who killed MJ with a massive overdose of Propofol.

TMZ broke numerous stories after MJ's death ... revealing how Jackson had at least 19 aliases to score Rx drugs from various doctors. It was well known in L.A. and Beverly Hills medical circles that MJ would doctor shop to find professionals who would open their surgery centers to give him Propofol. The doctors -- and dentists -- would justify the drug by saying they needed to put him under for minor procedures, such as acne removal.

We reported in one case ... a famed doctor used a gynecologist's office -- run by a doc who specialized in vaginal rejuvenation -- to perform a minor acne treatment under full anesthesia.

The Jackson family will argue AEG Live had a duty to monitor Murray. The problem is ... Jackson's the one who found Murray in the first place and that Murray administered Propofol long before the doc signed on to the "This Is It" tour.

AEG has a slew of doctors on its witness list ... to make the case that Jackson's addiction was in full bloom long before it entered the picture.

Katherine and the kids are asking for more than $40 BILLION in damages.