Cognizable Claims. Federal courts may consider an application for a writ of habeas corpus only on the ground that the prisoner's confinement violates the Constitution, laws, or treaties of the United States. Relief for a state violation of a federal statute will be granted only if the violation rises to the level of a “fundamental defect which inherently results in a complete miscarriage of justice” or is “inconsistent with the rudimentary demands of fair procedure.” Violations of state law are not cognizable in a § 2254 proceeding unless such violations are of constitutional magnitude. State violations of a treaty or other international obligation are not cognizable if the treaty or obligation has not been incorporated into domestic law.

Common habeas corpus claims include Sixth Amendment claims of failure to provide appointed counsel and ineffective assistance of counsel, Fifth Amendment claims concerning statements obtained in violation of Miranda v. Arizona, prosecutorial misconduct, significant judicial error, and insufficient evidence.

Claims of actual innocence are not cognizable without an independent constitutional violation in the underlying criminal proceedings that led to the prisoner's conviction. Some circuits will look only to evidence presented at trial and erroneously excluded evidence due to a trial-related constitutional violation, while other circuits will also consider evidence that only became available after trial. Claims that evidence obtained in violation of the Fourth Amendment was improperly admitted at trial are not cognizable if the state court provided the opportunity to litigate such claims fully and fairly. Claims of ineffective counsel based on mishandling of a Fourth Amendment objection, however, are cognizable habeas corpus claims.

Section 2254(d) permits habeas relief based on claims adjudicated on the merits in state court only when the state decision was (1) “contrary to, or involved an unreasonable application of, clearly established federal law, as determined by the Supreme Court” or (2) “based on an unreasonable determination of the facts.”

Federal courts apply the Brecht standard of harmless error in habeas proceedings. Under this standard, habeas relief is automatically granted for constitutional errors that are “structural defects,” whereas habeas relief for constitutionally significant “trial error [s]” is granted only when the error “had substantial and injurious effect or influence in determining the jury's verdict” or when a “deliberate and especially egregious error” warrants habeas relief even without substantial influence on jury's verdict. If the judge has “grave doubt,” meaning “the matter is so evenly balanced” as to whether the error had a substantial and injurious effect, the judge must find in favor of the habeas petitioner.

Under Teague v. Lane, habeas relief is generally not available if granting the relief would require the retroactive application of a “new constitutional rule” of criminal procedure that was not decided at the time the petitioner's conviction became final. There are two exceptions to the prohibition against applying new rules on habeas review. A “new rule” will be applied retroactively on habeas review of convictions that became final before the new rule was announced if: (1) the rule is substantive; or (2) the rule is a “watershed rule[] of criminal procedure” implicating fundamental fairness by mandating procedures central to an accurate determination of innocence or guilt.

The Teague nonretroactivity doctrine effectively obliges defendants to raise every novel potentially meritorious claim to the U.S. Supreme Court that the Teague doctrine may bar during habeas proceedings. Although the Teague nonretroactivity doctrine is a threshold question, which the court may raise sua sponte, the court must apply the doctrine if raised by the state. Additionally, courts must address properly raised arguments based on the Teague nonretroactivity doctrine even if the requirements of § 2254(d)(1) are met. However, Teague does not “limit a state court's authority to grant relief for violations of new rules of constitutional law when reviewing its own State's convictions;” thus, Teague does not prohibit state courts from applying a new rule to cases that were finalized before that new rule was announced.