Jose Padilla, a US Muslim convert, has been sentenced to more than 17 years in prison for plotting to kill people overseas and of supporting terrorism.
Padilla is a former Chicago gang member of Puerto Rican descent
Padilla was held for three-and-a-half years as an "enemy combatant" after his arrest in 2002 on suspicion of plotting a radioactive "dirty bomb" attack.
That charge was dropped and his case was moved to a civilian court after pressure from civil liberties groups.
He says he was tortured in military detention but officials deny this.
His mother told the BBC that this had been a "political case".
Padilla faced life in prison after his conviction in August.
Two other men, Lebanese-born Palestinian Adham Amin Hassoun and Jordanian-born Kifah Wael Jayyousi, were convicted on the same counts and sentenced to 15 years and eight months, and 12 years and eight months respectively.
The three defendants all denied the charges against them but, after a three-month trial in Miami, jurors took only a day-and-a-half to find them guilty.
In sentencing Padilla to 208 months in prison, US district court Judge Marcia Cooke said she had given the 37-year-old some credit for his detention as an enemy combatant following his arrest in May 2002 after returning from Pakistan.
Born to Puerto Rican parents in New York, moved to Chicago when 4
Involved in gang crime as a youth, jailed in 1991
Brought up a Catholic, thought to have converted to Islam in jail
Alleged to have learned bomb-making with al-Qaeda in Pakistan
Judge Cooke said she agreed with Padilla's lawyers that he had been subjected to "harsh conditions" and "extreme environmental stresses" at a Navy jail in South Carolina and that this warranted consideration.
The judge also dismissed prosecutors' claims that Padilla and his two co-defendants had done any more than conspire to murder, kidnap and maim, and provide material support for terrorism.
"There is no evidence that these defendants personally maimed, kidnapped or killed anyone in the United States or elsewhere," she said.
The chief evidence presented against Padilla at last year's trial was what the prosecution called an al-Qaeda application form bearing his fingerprints and date of birth that was found in Afghanistan.
FBI recordings of telephone conversations in Arabic between the defendants were also produced, containing, according to the prosecution, coded references to terrorist activity.
Their defence lawyers argued that the three men had links with countries such as Afghanistan, Bosnia and Chechnya because they had been involved in humanitarian aid for Muslims and said the charges against them were exaggerated.
Padilla's mother, Estela Ortega Lebron, said she was relieved that the sentence was not harsher.
Estela Ortega Lebron says she was relieved at the sentence
"You have to understand that the government was asking for 30 years to life sentence in prison," she told the BBC's Warren Bull in Miami.
"We have a chance to appeal, and in the appeal we're gonna do better."
While Jose Padilla faces 17 more years in prison, his mother says she is determined not to give up his case:
"This is not about Jose Padilla. This is a political case," said Mrs Ortega.
"I know that justice is going to be done on my son's behalf one of these days. It might not come today but it will come, believe me, it will."