The 37-year-old spent more than six years behind bars for various drug offenses.
He was sentenced to five years in prison for possessing and dealing drugs. But a judge later tacked on an additional four and a half years for breaking prison rules to get drugs behind bars. His release wasn't originally expected until 2018.
See photos of Michael Douglas and his son, Cameron, together:
Michael Douglas and son Cameron Douglas
Michael Douglas and son Cameron Douglas
HOLLYWOOD, CA - JUNE 25: Actor Michael Douglas and son Cameron Douglas arrive for the Premiere Of Disney And Marvel's 'Ant-Man And The Wasp' held at the El Capitan Theater on June 25, 2018 in Hollywood, California. (Photo by Albert L. Ortega/Getty Images)
Actor Michael Douglas (L) and Cameron Douglas attend the World Premiere of Marvel Studios 'Ant-Man and The Wasp' at the El Capitan Theater, on June 25, 2018, in Hollywood, California. (Photo by Valerie MACON / AFP) (Photo credit should read VALERIE MACON/AFP/Getty Images)
LOS ANGELES, CA - JUNE 20: Michael Douglas and his son, Cameron Douglas are seen on June 20, 2018 in Los Angeles, California. (Photo by BG002/Bauer-Griffin/GC Images)
LOS ANGELES, CA - NOVEMBER 09: (L-R) Michael Douglas, Catherine Zeta-Jones and Cameron Douglas attend the Los Angeles Mission Legacy of Vision Gala at Four Seasons Hotel Los Angeles at Beverly Hills on November 9, 2017 in Los Angeles, California. (Photo by Tibrina Hobson/Getty Images)
404806 04: Actor Michael Douglas (R) and his son Cameron Douglas arrive at the Conde Nast Traveler Hot List party at the W Hotel May 1, 2002 in New York City. (Photo by Mark Mainz/Getty Images)
Kirk Douglas, Anne Douglas, Diandra Douglas, Cameron Douglas, and Michael Douglas (Photo by Ron Galella, Ltd./WireImage)
Michael Douglas, Cameron Douglas, and Diandra Douglas (Photo by Ron Galella/WireImage)
Michael & Cameron Douglas during Holyfield v. Tyson II in Las Vegas, Nevada, United States. (Photo by Jeff Kravitz/FilmMagic, Inc)
UNITED STATES - MAY 26: Diana Douglas Darrid with her grandson Cameron Douglas (l.) and her son Michael Douglas (r.) attending book party for Darrid's 'In The Wings: A Memoir' at Sardi's. (Photo by Richard Corkery/NY Daily News Archive via Getty Images)
UNITED STATES - MARCH 15: Actors Lou Gossett Jr., Michael Douglas and son Cameron Douglas (l. to r.) watch as the New Jersey Nets defeat the Miami Heat, 97-78, at the Continental Airlines Arena. (Photo by Howard Earl Simmons/NY Daily News Archive via Getty Images)
Michael Douglas, mother, and son Cameron Douglas (Photo by Jim Smeal/WireImage)
NEW YORK - DECEMBER 17: (ITALY OUT) Cameron, Kirk and Michael Douglas stand in front of Cipriani's Restaurant December 17, 2002 in New York City, New York. (Photo by Arnaldo Magnani/Getty Images)
LOS ANGELES - APRIL 7: Actor/producer Michael Douglas (L) and son actor Cameron Douglas arrive at the premiere of 'It Runs In The Family' at the Bruin Theater on April 7, 2003 in Los Angeles, California. (Photo by Kevin Winter/Getty Images)
NEW YORK - APRIL 13: (U.S. TABS & HOLLYWOOD REPORTER OUT) (L to R) Diana Douglas, Kirk Douglas, Michael Douglas and Cameron Douglas arrive at the New York premiere of 'It Runs In The Family' at the Loews Lincoln Square Theater April 13, 2003 in New York City. (Photo by Scott Gries/Getty Images)
Cameron Douglas and Michael Douglas (Photo by Mark Sullivan/WireImage)
PROVIDENCIALES TURKS AND CAICOS ISLANDS, BWI- JANUARY 05: ***PREMIUM PRICING;USAGE IN POSITIVE STORY ONLY;GETTY IMAGES EXCLUSIVE;TABLOIDS OUT*** Actor Michael Douglas, actress Catherine Zeta-Jones with Cameron Douglas and his girlfirend Kelly Sotton Dellis Cay on Turk and Caicos while on holiday in the Caribean January 5, 2007 in Providenciales Turks and Caicos Islands. (Photo by Frazer Harrison/Getty Images).
CULVER CITY, CA - MARCH 06: Cameron Douglas, actor Michael Douglas and actress Catherine Zeta-Jones attend Kirk Douglas' one man show 'Before I Forget' at The Kirk Douglas Theatre on March 6, 2009 in Culver City, California. (Photo by Jason LaVeris/FilmMagic)
April 27, 2009 Hollywood, Ca.; Cameron Douglas and Michael Douglas; 'Ghosts of Girlfriends Past' World Premiere; Held at Grauman's Chinese Theatre (Photo by Gregg DeGuire/FilmMagic)
Actor Michael Douglas and Cameron Douglas attend a performance of Hairspray on October 23, 2002 at the Neil Simon Theater in New York City. (Photo by Ron Galella, Ltd./WireImage)
"They've got to do their time like everybody else, but why would you not want them to see their family? Why would you not want them to get some (re)sources?" Michael Douglas told Extra.
In 2013, a New York appeals court upheld Cameron Douglas' sentence for getting drugs behind bars. At the time, the more-than-four-year sentence was considered possibly the "longest-ever federal prison sentence imposed for the simple possession of drugs for personal use behind bars," according to Drug Policy Alliance.
Cameron Douglas is reportedly staying in a halfway house in Brooklyn, New York.
This video includes clips from ABC and Fox News and images from Getty Images.