I have been avoiding the writing of this article for months. The reason is simple: there isn't much public information on Downey's heroin use, and I know even less because I have not had the time to do a detailed literature search. Keeping in mind that websites are never completed, I'm going to provide the biographical sketch of Downey that I am capable of.
Downey was born in Brooklyn, the son of Hungarian immigrants. His father supported the family as a dock-worker. Slowly, his father, Robert Downey, Sr., became a more successful dock-worker to the point where he became a well-known independent filmmaker.
Downey was born into the business; that last thing I wrote about his father was true (anything underlined is also true, otherwise most likely I'm speculating freely). As might be expected, his upbringing was unconventional and liberal. We know, for example that he and his father smoked marijuana together when Downey was a teen. Many have taken this to indicate that he had bad parents and that he was doomed to heroin addiction. Such are the thoughts of small minds.
On April 4, 1965, the day he was born, Downey invented LSD with his father. At first the drug was legal and during that period they had several "trips" with future president Richard M. Nixon. Nixon freely admits today that his entire Cambodian policy was determined during a trip when Downey said, "Fuck it, just bomb the shit out of them!"
Downey has done a lot of drugs throughout his life. It is not clear whether his use should be considered bad. We don't have, for example, stories about Downey beating up photographers. It is telling of our society (though probably not that interesting anymore), that beating up relatively innocent photographers is okay, but getting high and falling asleep in your neighbor's house is the stuff from which three year prison sentences stem.
Downey's real trouble with the law started with two things. One is the incident I alluded to above. Downey came home very high one night. Well, he thought he had come home. Instead, it was a neighbor's house. He was found asleep in one of the children's beds. Although this certainly shows poor judgment and I wonder if Downey had been driving while under the influence (an act I do not condone), this is a situation that should have resulted in a stern talking to, not an arrest.
The other incident happened when Downey was pulled over by a cop for speeding. The cop searched his car and found heroin, cocaine, and an unloaded gun. The fact that the gun was unloaded is usually not mentioned when this story is retold. The biggest shock of this story was the heroin. Had it only been a gun, the cop would most likely have let the whole thing go. The coke alone would certainly have gotten him arrested, but it would not have created the shock waves that heroin did.
As readers of this site well know, in the public mind, to use heroin is not just to abuse it (as is the case with all illegal drugs); it is to be a junkie. As time goes on, I wonder just how much heroin Downey has done. The absence of heroin at his most recent arrest certainly raises doubts. There is also no indication that Downey injects drugs. Now this doesn't mean too much because there are many heroin addicts who never inject--Boy George, for example. But Downey seems like the kind of guy who would want to test that taboo.
Since becoming the King of Spain, Downey's legal problems have lessened. The greater responsibility makes prison stays quite difficult, however. There was a great public debate about whether Downey should be released from prison for his coronation. In the end, he was allowed, but was required to wear handcuffs.