From the NJ Star-Ledger:
"Chong was arrested in 2003 with 54 others in the Drug Enforcement Administration's "Operation Pipe Dreams." Chong was selling bongs and pipes on the Internet as Nice Dreams Enterprises. He was the only one of the 55 arrested to serve jail time."
Selective prosecution?
Worse than that, he took a plea so they wouldn't prosecute his wife and son. Nothing like a little leverage to ensure a defendant toes the line.
After his guilty plea, he probably shouldn't have joked around with the press about putting the criminal case in his next movie with Cheech Marin. It seems the federal prosecutors and judge felt that showed a lack of remorse. He could gave gotten community service.
He was offered home detention, by the way, but chose to go to jail. The martyr status is probably better for his career.