Michael Douglas' son travelled coast to coast dealing large quantities of methamphetamine, a criminal complaint said.
The complaint in federal court in Manhattan, made public last night, says Cameron Douglas was paid tens of thousands of dollars trafficking the drug - referred to in transactions by the codewords "pastry" or "bath salts" - since 2006.
Cash and drugs were routinely exchanged through shippers like FedEx, the court papers said.
The 30-year-old son of the Oscar-winning actor was arrested on July 28 at the trendy Hotel Gansevoort in Manhattan. His lawyer, Nicholas DeFeis, declined to comment.
Federal authorities have refused to discuss whether Douglas remained behind bars or any other aspect of the case.
The complaint, drawn up by a Drug Enforcement Administration agent, details allegations based on information provided by three unnamed crystal meth users and dealers.
The users - including someone who once worked for Douglas - have pleaded guilty and agreed to co-operate with the investigation.
The complaint said that in one deal in 2006, a co-operator shipped cash under a fake name to Douglas at a California hotel. A few days later, it said, Douglas delivered a pound of methamphetamine to the informant at a Manhattan hotel.
In 2007, according to another informant, Douglas was paid 48,000 dollars (£28,400) at a Manhattan apartment. The informant later received a pound of crystal meth through FedEx from Santa Barbara, California, the complaint said.
In June and July, negotiations for more drugs were secretly recorded on wiretaps of mobile phones and a co-operator's hotel room in Manhattan, the complaint said.
Douglas, in one recording at the hotel, "acknowledged his prior history selling crystal meth" and "indicated that he continued to sell crystal meth".
In a separate recorded phone conversation, investigators said he spoke of "sending out a pastry" to a co-operator, and also asked: "Did you get a chance to ... smell any of the salts or anything like that?"
Cameron Douglas has acted in movies including 2003's It Runs In The Family," starring his father and grandfather Kirk Douglas.
He was also arrested in California in 2007 on cocaine possession charges. His lawyer then said the arresting officer did not do his job properly.