The U.S. Supreme Court case Wetzel v. Lambert (2011) revolved around James Lambert, a man convicted of murder in Pennsylvania who sought to have his conviction overturned on the grounds that prosecutors had withheld evidence during his trial. The Third Circuit Court of Appeals initially ruled in favor of Lambert, stating that he was entitled to relief under the precedent set by Brady v. Maryland - which requires prosecutors to disclose exculpatory evidence - because there was reasonable probability that disclosure could have changed the outcome of proceedings. However, upon reaching the Supreme Court, this decision was reversed unanimously per curiam (without identifying individual justice's votes). The court held that not only did Lambert fail to demonstrate due diligence in pursuing state remedies for his claim as required by federal law but also failed to establish "materiality" under Brady standard i.e., he didn't show a reasonable likelihood that withheld information would've led jury towards different verdict if disclosed earlier. This ruling reinforced both importance and limitations of Brady rule while emphasizing need for defendants seeking post-conviction relief based on prosecutorial misconduct claims must meet stringent requirements before their cases can be reconsidered.

In the dissenting opinion for Wetzel v. Lambert, Justice Scalia disagreed with the majority's decision to grant relief based on a Brady violation (the withholding of evidence favorable to an accused). He argued that there was no reasonable probability that disclosure of the suppressed evidence would have led to a different result in Lambert’s trial. The undisclosed document merely contained information about another potential suspect who had been investigated and cleared by police before Lambert's trial began. According to Scalia, this did not undermine confidence in his conviction because it didn't establish any connection between this other individual and the crime scene or victim. Furthermore, he stated that even if defense counsel could have used this document during cross-examination, it wouldn’t necessarily change jurors' minds given strong eyewitness testimony against Lambert. Thus, Scalia believed granting habeas corpus relief under these circumstances expanded Brady beyond its proper scope.