Let's say, for example, a person previously testified in a criminal case that they saw someone murder someone else. Based largely on this testimony, a jury convicts the defendant.

Later on, the witness gets into some personal issues with their romantic partner, and a messy divorce case follows. In that case, they are found to be a habitual liar who will go to great lengths to manipulate others.

In this situation, would the original defendant have grounds to get their conviction overturned? I'm basically asking if "witness reliability" is something that extends between cases or is it an idea that only pertains on a case-by-case basis (i.e. treated completely separately).

  • There is an immense amount of U.S. law on point but I'd be curious to see how Canada handles it.
    – ohwilleke
    Nov 29, 2023 at 23:46
  • @ohwilleke I would appreciate a post about the U.S. too!
    – AlanSTACK
    Nov 29, 2023 at 23:51
  • 2
    Too depressing for today. Maybe later.
    – ohwilleke
    Nov 30, 2023 at 0:16
  • @ohwilleke I await you with bated breath.
    – AlanSTACK
    Jan 31 at 0:30

2 Answers 2


Let's say, for example, a person previously testified in a criminal case that they saw someone murder someone else. Based largely on this testimony, a jury convicts the defendant.

Later on, the witness gets into some personal issues with their romantic partner, and a messy divorce case follows. In that case, they are found to be a habitual liar who will go to great lengths to manipulate others.

In this situation, would the original defendant have grounds to get their conviction overturned?

Probably not. Unless someone's constitutional rights are violated by prosecutors in the handling of the case, even evidence that casts gross doubt on the accuracy of a conviction, even in a death penalty case, is only rarely successful in overturning the validity of a conviction.

There have been many U.S. cases where someone else has confessed to committing the crime and the conviction was not overturned.

The procedural barriers to this kind of collateral attack on a conviction are great, in part, due to the Antiterrorism and Effective Death Penalty Act of 1996 which imposes daunting barriers to overturning a conviction. Indeed, whether unequivocal proof of actual factual innocence is a legally recognized basis for overturning a conviction (while often raised), remains an open question in U.S. law. Conservative judges tend to opine that it is not.

For example, Justice Scalia wrote in the case of Troy Davis, in the face of post-trial recantations by almost all of the witnesses against him and a confession of guilt for the murder by someone else who is in prison that:

This Court has never held that the Constitution forbids the execution of a convicted defendant who has had a full and fair trial but is later able to convince a habeas court that he is "actually" innocent.

Professor Alan Dershowitz, at Harvard Law School, explains what this means:

Let us be clear precisely what [Scalia's dissent] means. If a defendant were convicted, after a constitutionally unflawed trial, of murdering his wife, and then came to the Supreme Court with his very much alive wife at his side, and sought a new trial based on newly discovered evidence (namely that his wife was alive), these two justices would tell him, in effect: "Look, your wife may be alive as a matter of fact, but as a matter of constitutional law, she's dead, and as for you, Mr. Innocent Defendant, you're dead, too, since there is no constitutional right not to be executed merely because you're innocent."

Denial of relief in cases like the case of Troy Davis are the norm in the United States and not the exception.

In the case of Richard Glossip in Oklahoma, even the state’s Republican attorney general says he should not be executed and is probably innocent, but so far the courts (and pardon boards) have refused to set aside his execution. The U.S. Supreme Court recently granted certiorari in the case, but is probably more likely to affirm Mr. Glossip's execution than to vacate it.

The federal courts play a very small role in overturning state court convictions and sentences, granting relief about once per 20,000 inmates per year in non-capital cases, and about once per eight people sentenced to death (often vacating the death sentence but retaining a lengthy prison sentence).

Federal habeas corpus exonerations for actual innocence under current law (which some judges allow while the law on this point remains unresolved at the U.S. Supreme Court level) probably results relief for not more than about 3 people per year in non-capital cases, and 1-2 people in a capital case per year, nationwide, in the United States, where millions of people are incarcerated.

For example (my source link for this quote has gone dead):

In 2004, there were about 19,000 non-capital federal habeas corpus petitions filed and there were about 210 capital federal habeas corpus petitions filed in U.S. District Court. There are about 60 habeas corpus cases filed in the U.S. Supreme Court's original jurisdiction each year. The U.S. Courts of Appeal do not have original jurisdiction over habeas corpus petitions. . . . As of 2004, the percentage of federal habeas corpus petitions involving state death sentences was still about 1% of the total. . . . About 63% of issues raised in habeas corpus petitions by state court prisoners are dismissed on procedural grounds and about 35% of those issues are dismissed on the merits, while about 2% are either resolved favorable to the prisoner on the merits or remanded to a state court for further proceedings at the U.S. District Court level. . . . [A]study found that when habeas corpus petitions in death penalty cases were traced from conviction to completition of the case that there was "a 40 percent success rate in all capital cases from 1978 to 1995." . . . [Another study] puts the success rate in habeas corpus cases involving death row inmates even higher, finding that between "1976 and 1991, approximately 47% of the habeas petitions filed by death row inmates were granted." . . . about 20% of successful habeas corpus petitions involve death penalty cases. . . . As of 1991, the average number of federal habeas corpus petitions filed in the United States was 14 per 1,000 people in state prison, but this ranged greatly from state to state from a low a 4 per 1,000 in Rhode Island to a high of 37 per 1,000 in Missouri.

Reasonable estimates of wrongful conviction rates in the U.S. are on the order of 1-2% of convictions, about half following jury trials and about half from guilty pleas to crimes that the defendant didn't commit due to low mental capacity, despair, or a favorable deal compared to the risk of a very severely punished wrongful conviction of trial.

Similarly, in a 2007 case, Justice Thomas (joined by four of his conservative colleagues) faults a litigant for relying upon a deadline set forth in a court order from a District Court judge incorrectly and denies relief. The four liberals on the U.S. Supreme Court dissent, noting that:

It is intolerable for the judicial system to treat people this way, and there is not even a technical justification for condoning this bait and switch.

Even mistakes of law by a court that are not fault of the convicted defendant are held against them:

Ezell Gilbert is now before us asking to be relieved of the consequences of a mistake we made in his direct appeal in 1998. He told us then that the District Court was wrong in sentencing him substantially more harshly based on that court’s decision that carrying a concealed weapon is a crime of violence. We rejected his argument, and affirmed his sentence of more than 24 years. United States v. Gilbert, 138 F.3d 1371 (11th Cir. 1998). We did this on a record containing the District Judge’s clear statement that the sentence was longer than he would have imposed, but for the then-mandatory Sentencing Guidelines. Id. at 1372–73. It turns out, of course, that Mr. Gilbert was right and we were wrong. Carrying a concealed weapon is not a crime of violence. We said so, belatedly for Mr. Gilbert, in United States v Archer, 531 F.3d 1347 (11th Cir. 2008).

The effects of our mistake are quite dire for Mr. Gilbert, insofar as his properly calculated (and advisory) guideline range would today be 130–162 months, or approximately 11 to 13 years. As I write this, I understand that he has already served more than fourteen years in prison. And yet the majority opinion tells Mr. Gilbert that the laws and Constitution of this country offer him no relief.

From the dissenting opinion of Judge Martin from an en banc ruling of the 11th Circuit in an appeal of a U.S. District Court denial of a habeas corpus petition. The majority opinion by Judge Carnes (at the same link) opens with the following:

Ezell Gilbert, a federal prisoner, wants to have an error of law in the calculation of his sentence corrected based upon a Supreme Court decision interpreting the sentencing guidelines, even though that decision was issued eleven years after he was sentenced. Gilbert insists that prisoners have a right to have errors in the calculation of their sentences corrected no matter how long it has been since the sentences were imposed. . . . The principles of policy that limit the right to be resentenced in accord with the latest guidelines decisions are those regarding finality of judgment and the important interests that finality promotes. For reasons we will discuss, the statutory provisions and the decisions furthering finality of judgment are strong enough to hold their own against Gilbert’s claimed right to have a long-ago error in calculating his sentence corrected.

The Fifth Circuit, in a recent case, went even further in December of 2022, somewhat contradictorily arguing that actual innocent is the only grounds for relief:

Federal law explicitly authorizes federal courts to review convictions and sentences handed down by state courts, and to invalidate them if a prisoner is held “in custody in violation of the Constitution or laws or treaties of the United States.”

Last Thursday, however, a far-right panel of the United States Court of Appeals for the Fifth Circuit effectively eliminated state prisoners’ right to seek what is known as a “writ of habeas corpus” when they are imprisoned in violation of the Constitution or federal law, except in cases of “factual innocence.”

Among other things, this means that someone who is “factually guilty” of an unconstitutional crime — such as violating a Jim Crow law or a law prohibiting individuals from criticizing the president — would be stripped of their habeas rights in federal court. It could also potentially enable abusive conduct by police and prosecutors, such as coerced confessions or warrantless searches, by removing nearly all federal supervision of states that overlook such violations.

Judge Andrew Oldham’s decision in Crawford v. Cain is completely lawless. It finds this novel requirement that an unconstitutional or illegal conviction or sentence must stand, unless the prisoner shows they are innocent, within a federal statute that states that federal courts hearing habeas cases “shall summarily hear and determine the facts, and dispose of the matter as law and justice require.” Oldham, along with the two other Republican-appointed judges who joined his opinion, claims that only factual innocence “satisfies the law-and-justice requirement.”

From Vox. The three judge panel ruling is here.

When justice is served in a collateral attack on a criminal conviction in the United States, it is something approaching a miracle if it does anything other than convert a death penalty sentence into a life in prison without possibility of parole sentence.

The quality of legal representation of people, even people facing the death penalty, in states like Texas, also routinely shocks the conscience with no relief for the incarcerated person.

  • Damn. Truly depressing. How do you sleep at night? (P.S. some of your links are dead)
    – AlanSTACK
    Jan 31 at 3:23
  • @AlanSTACK I pulled the links mostly from old blog posts and media articles without checking them. I may or may not be able to restore some of them. "How do you sleep at night?" This is one of the reasons I don't practice criminal law and post-conviction review law.
    – ohwilleke
    Jan 31 at 3:35
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    @AlanSTACK To a degree, realizing the issue and talking about it helps making people aware of the flaws in the system. Only if people are aware of the flaws, they can make an informed choice by voting people into power who are willing to make a change. If people vote for the Status Quo, the imperfect system stays. The first step to change is to go and vote for it, and to talk to your representatives to make sure they know what you want them to do.
    – Trish
    Feb 1 at 7:48
  • @Trish My confidence in the electoral process is essentially zero. At this point in time, the system is running purely on corporate quid pro quo, sheer bureaucratic momentum, and rabid special interest groups. I'm just here for the money, now.
    – AlanSTACK
    Feb 1 at 9:00

A jury should be cautioned about a Crown witness who provides inculpatory evidence when that witness has an established history of disreputable conduct that the judge views to impair the worth of the witness. The judge should "attract the jury's attention to the risks of adopting, without more, the evidence of the witness." This is known as a Vetrovec warning.

Factors do include criminal activity and previous lies under oath.

A judge's decision to give or not give such a warning is discretionary and is treated with substantial deference on appeal (R. v. Van Every, 2016 ONCA 87, at para. 73). If the information that would have led a judge to issue a Vetrovec warning did not even become available until after the trial, this would not be a ground to challenge the conviction.

  • What do you mean by "extremely deferentially," as in being polite but not significantly impactful in appeals, or as in holding the majority of the weight in appeals?
    – AlanSTACK
    Nov 30, 2023 at 1:20
  • Really? This isn't grounds for retroactively challenging a conviction? So, for example, a police officer who was later found lying in a different case would still be considered "reliable" in his prior testimonies?
    – AlanSTACK
    Nov 30, 2023 at 1:22
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    @AlanSTACK Common law jurisdictions traditionally offer immense importance and deference to jury decisions, and not enabling relitigation. Whether or not witness testimony is "reliable" is a decision made by the jury. Sometimes they decide a bit of testimony isn't reliable, and they don't use it in making their decision; sometimes they decide it is reliable and use it. The system makes the jury's decisions and process largely sacrosanct, and does not try to retroactively question and undo them. That defeats the entire purpose of the jury of putting this in the people's hands. Jan 31 at 6:46

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