DETROIT (CNN) -- The man who smuggled a bomb in his underwear aboard a commercial airliner on Christmas Day in 2009 has been sentenced to life in prison, months after he pleaded guilty for his role in what officials later determined was an al Qaeda plot.
U.S. District Judge Nancy Edmunds imposed a life sentence Thursday on Umar Farouk AbdulMutallab, who entered the courtroom in Detroit wearing an oversized white T-shirt and a white skull cap. His hands were unshackled once he entered.
He argued a life sentence would be "cruel and unusual punishment," as well as unconstitutional. The judge rejected the argument.
Prosecutors brought a video showing the detonation of a replica of the device AbdulMutallab attempted to use. The judge ruled that the video could be shown during the sentencing hearing.
In the sentencing report, prosecutors called now 25-year-old Nigerian "an unrepentant would-be mass murderer, who views his crimes as divinely inspired and blessed."
AbdulMutallab previously pleaded not guilty to the eight charges against him, which include attempted use of a weapon of mass destruction and conspiracy to commit an act of terrorism.
On December 25, 2009, passengers aboard a Northwest Airlines flight from Amsterdam heard a loud noise on the plane as it descended toward Detroit. Witnesses described it as sounding much like a firecracker.
The device failed, but AbdulMutallab became enveloped in a fireball that spread to the wall and carpeting of the plane.
Four passengers quickly restrained him and helped put out the fire, witnesses said, and he was escorted up to the first-class section of the plane and taken into custody by authorities when it landed.
AbdulMutallab later acknowledged in a courtroom statement that he had traveled to Yemen and was "greatly inspired" to participate in such a plot by U.S.-born militant cleric Anwar al-Awlaki, who was killed by a U.S. drone strike in Yemen in September.
U.S. officials later said the terror group al Qaeda in the Arabian Peninsula had helped foment the failed attack.
"I carried with me an explosive device to avenge the killing of innocent Muslims," AbdulMutallab said in the statement, adding that the failed plot was in retaliation for "U.S. tyranny and oppression of Muslims."
The flight was carrying 289 people.
The decision to try AbdulMutallab in a civilian court prompted controversy at the time, particularly among Republican lawmakers pushing for a military tribunal. He's been held at a Michigan federal prison since 2009.
Prosecutors, however, said the case demonstrated the value of civilian courts.
"We should not limit ourselves to military tribunals," said U.S. District Attorney Barbara McQuade. The case shows "the world that our system of justice works."
CNN's Kiran Khalid contributed to this report.