Date on which a federal judge overturned Albert Woodfox's second murder conviction in the 1972 stabbing death of a prison guard during a riot and ordered the release of the 68-year-old from the Louisiana State Penitentiary at Angola, where he's being held in solitary confinement: 6/8/2015

Days later that a federal appeals court blocked the release of Woodfox, who maintains his innocence in the guard's death, while the court considers an appeal filed by Louisiana Attorney General Buddy Caldwell: 4

Years that Woodfox, who was initially imprisoned at Angola for armed robbery, has been held in solitary, with the warden having cited his involvement with the Black Panthers to justify the isolation: 43

Hours per day Woodfox is confined to his 8-by-12 foot cell: 23

Times per week he's permitted to exercise: 3

Year in which the United Nations called for Woodfox's release, saying that being kept in solitary confinement for more than four decades "clearly amounts to torture": 2013

Years that Herman Wallace, another Black Panther who along with Woodfox and Robert King was also convicted in the guard's death, was held in solitary confinement at the same Louisiana prison, where the trio came to be known as the "Angola Three": 41

Days after his release in October 2013 that Wallace died of cancer: 1

Years Damon Thibodeaux spent in solitary confinement at Angola before DNA records showed he couldn't be responsible for the murder and sexual assault of which he had been convicted: 15

Number of prisoners estimated to be held in solitary confinement in the U.S.: 80,000

According to one independent investigation, percent of prisoners in solitary housing units found to be mentally ill, which is much higher than in the general prison population: 64

Number of states that still place death row inmates in some type of solitary confinement: 31

Number of prisoners on Virginia's death row who are suing to end the practice of automatic solitary confinement for those with death sentences: 4

In a previous, unsuccessful challenge to Virginia's policy of solitary confinement for death-row inmates, number of former corrections officials who submitted a friend-of-the-court brief arguing the practice was "harmful and unnecessary to institutional safety": 9

Year in which U.S. Rep. Cedric Richmond, a Louisiana Democrat, introduced a bill to study the practice of solitary confinement nationally and recommend reforms: 2014

Number of co-sponsors who signed on to that bill, which stalled in committee: 23

(Click on figure to go to source.)