In the federal law of the United States, the Schlup-House "Actual Innocence" Doctrine is an evolving concept governing the procedural aspects of cases where persons convicted in state-court criminal proceedings too long ago to challenge those convictions in state court have filed habeas corpus  proceedings in federal court  to have their convictions overturned because of new evidence. The new evidence often results from DNA analyses or other technologies that did not exist until after the time limit for challenging the conviction in state court had expired -- many of them analytic techniques of pathology and/or forensics that have been so widely depicted in popular television shows as to be considered commonplace -- and there are now individuals and organizations whose business purpose is to get old criminal convictions overturned. 
The doctrine is named for two U.S. Supreme Court opinions, Schlup v. Delo, 513 U.S. 298 (1995), and House v. Bell, 547 U.S. ____, 126 S. Ct. 2064 (2006), that applied settled legal principles to a type of case arising more and more often: state prisoners filing a series of habeas corpus cases in federal court, another one each time a new piece of evidence that they had not committed the crime becomes available.
In Schlup the high court ruled  that the legal standard that applies "when a petitioner who has been sentenced to death raises a claim of actual innocence" in a federal habeas case is that of Murray v. Carrier, 477 U.S. 478 (1968),  not "the more stringent" standard of Sawyer v. Whitley, 505 U.S. 333 (1992). Carrier requires the petitioner to prove to the court that "a constitutional violation has probably resulted in the conviction of one who is actually innocent," but Sawyer would require a petitioner to prove to the court "that, but for a constitutional error, no reasonable juror would have found the petitioner eligible for the death penalty under the applicable state law."
In House the court quoted from Carrier and Schlup in reiterating that a habeas claim does require the prisoner to produce "new reliable evidence ... not presented at trial" but that "rather than requiring absolute certainty about guilt or innocence," what the petitioner has to prove to the court is "that more likely than not, in light of the new evidence, no reasonable juror would find him guilty beyond a reasonable doubt." To make that point clear, the court said this is a totally different legal standard from the one set forth in Jackson v. Virginia, 443 U.S. 307 (1979), which applies when the petitioner claims the evidence against him at his trial was insufficient to support his conviction. The Schlup-House standard applies when the habeas court is considering "evidence the trial jury did not have before it, [so] the inquiry requires the federal court to assess how reasonable jurors would react to the overall, newly supplemented record."
Thus, the Schlup-House doctrine says the "burden of proof" a state prisoner must meet to be granted habeas in federal court is the "preponderance of the evidence" civil-trial standard, not the "beyond a reasonable doubt" criminal-trial standard: The federal judge hearing the habeas case must decide whether a reasonable juror at the criminal trial in state court, after considering all the evidence that was presented at that trial together with whatever additional evidence has now been presented to the habeas court, could have had a reasonable doubt that the petitioner was guilty. If so, the habeas petition must be granted, invalidating the conviction. The habeas judge does not have to find a juror would have believed the petitioner was actually, factually innocent, merely that a juror would have found the petitioner legally "not guilty."
- Habeas corpus, sometimes called "the Great Writ," is one of the six prerogative writs that developed in England following the Norman Conquest (in 1066). Deriving from concepts of the pre-Conquest Anglo-Saxon common law, and one of the rights itemized in Magna Carta (in 1215), habeas corpus is a writ (= court order) directing someone holding someone else in custody (= imprisonment) to "have his body" (in Latin) in the issuing court at the time specified in the writ, that is, to bring the prisoner (to tell his side of it) and explain to the court the legal justification for holding him prisoner. During the American Civil War (in 1861 to 1864), President Abraham Lincoln suspended the writ of habeas corpus (and ignored the Supreme Court when it ruled that was unconstitutional), a situation that legal scholars still debate heatedly today.
- Petitions to federal courts by persons in state prison (for violating state laws) and claiming they were convicted in violation of the U.S. Constitution are governed by a specific statute in the U.S. Code: 28 U.S.C. §2254. (A separate statute, 28 U.S.C. §2241, governs habeas suits by federal prisoners, that is, those who were convicted in federal courts of federal crimes and are claiming they are in federal prison unconstitutionally.) Before petitioning a federal court for habeas, §2254 requires a state prisoner to have "exhausted the remedies available in the courts of the State," meaning the prisoner has to have tried all the procedures the state's courts provide for seeking post-conviction relief and been unsuccessful.
- Those individuals include forensic scientists and investigators as well as attorneys. The organizations include laboratories and law schools' clinics -- one such is the Innocence Project.
- In Herrera v. Collins, 506 U.S. 390 (1993), the Supreme Court had said that "in a capital case a truly persuasive demonstration of 'actual innocence' " might be enough to support a habeas claim, and in House the court said that is true, but such a case has not yet been presented to the court, so the court has never actually ruled that way. (Petitioner House had not met that standard, but he did meet the applicable Carrier standard, so the Supreme Court ruled the trial court could adjudicate his habeas petition.)
- Carrier and two other cases decided at the same time -- Kuhlmann v. Wilson, 477 U.S. 436 (1986), and Smith v. Murray, 477 U.S. 527 (1986) -- established the "miscarriage of justice" exception to the general rule that a federal court will not consider repeated habeas petitions from the same prisoner.
Full Text of Selected Court Opinions
- House v. Bell, 547 U.S. ____, 126 S. Ct. 2064 (2006) on FindLaw
- Jackson v. Virginia, 443 U.S. 307 (1979) on FindLaw
- Sawyer v. Whitley, 505 U.S. 333 (1992) on FindLaw
- Schlup v. Delo, 513 U.S. 298 (1995) on FindLaw
Federal Habeas Corpus Statutes