The judge says 73-year-old Joseph "Uncle Joe" Ligambi remains a danger to the community.
A jury last last month deadlocked or acquitted him of charges involving gambling, loansharking and extortion activities. The jury convicted three defendants of racketeering conspiracy, but deadlocked on that central count for both Ligambi and his nephew, George Borgesi.
Authorities say Ligambi has been the acting boss in Philadelphia since Joseph "Skinny Joey" Merlino went to prison in 1999.
They say it's unclear who will run it now that Merlino is out, although he is now living in south Florida.
Ligambi's retrial is set for April. He once spent a decade in prison for murder, but the conviction was overturned.