In the rare instance that a human [[soul]] is able to escape from Hell, unless there is divine intervention, a damned soul cannot gain entry into [[Heaven]]. There have been only three known exceptions to the rule: [[Dean Winchester]], who was sent to Hell after his [[crossroads]] [[deal]] came up, but upon being killed by the [[hunter]] duo of [[Walt and Roy]], Dean was allowed entry into Heaven in order for the angel [[Joshua]] to pass along a message from [[God]] to the Winchesters. After [[Bobby Singer]] was killed by the [[Leviathan]] [[Dick Roman]], Crowley ensured through the use of the rogue [[reaper]] [[Ajay]], that Bobby would end up in Hell. Bobby was later rescued by [[Sam Winchester]] for the second [[trial]] to close to Gates of Hell, which required that "An innocent soul has to be rescued from Hell and delivered unto Heaven", which allowed Bobby entry. For years it was unknown what became of [[John Winchester]] after his escape from Hell, after the second death of [[Mary Winchester]], [[Castiel]] confirmed that John was in Heaven with Mary, telling Sam and Dean that Mary was with "John, and there's no sorrow. There's no guilt. Just joy."
Being the servants of [[Death]], reapers have access to all spiritual planes in existence. As a favor to Crowley, the then reaper [[Billie]], was able to create an entrance on earth to Limbo for Dean Winchester.
===Restriction and Confinement===
[[Samhain]] can only be released from Hell every six hundred years. His release requires two powerful [[witch]]es performing three blood sacrifices over three days, the last day being October 31st (Halloween).<ref name="four07">[[4.07 It's the Great Pumpkin, Sam Winchester]]</ref> [[Lilith]] was said to be imprisoned deep in the pit by Azazel, who claimed her release would not be easy, but succeeded when the [[Devil's Gate in Wyoming]] was opened and released hundreds of demons, including Lilith.
When a demon is exorcised, escape to earth becomes more difficult, but is not impossible. After the [[Jeffrey!Demon|demon possessing]] [[Jeffrey]] gave "state secrets" to the Winchesters, the demon was placed in lockdown, and could only be summoned to earth via a specific ritual.