In the most common types of habeas corpus proceedings in the United States federal courts, a certificate of appealability is a legal document that must be issued before a petitioner may appeal from a denial of the writ. The certificate may only be issued when the petitioner has made a "substantial showing of the denial of a constitutional right." The application may be made explicitly, but a notice of appeal made without a certificate of appealability is treated as an implicit application for the certificate. "To obtain a , the must make a request to a district or circuit court judge. In the application, the includes the issues he wishes to raise on appeal. In general, the application process is informal, there is no hearing, and the government rarely files a brief in response to the prisoner's request. The determination is simply made in chambers. If the district court judge denies the request, the may apply to the circuit judge. In addition, a notice of appeal to the circuit court can be treated as a request for a COA." Under Rule 22 of the Federal Rules of Appellate Procedure, "a certificate of appealability is not required when a state or its representative or the United States or its representative appeals." A certificate of appealability is also not required for petitioners seeking a writ of coram nobis; however, the writ of coram nobis is only available for those who are no longer in-custody and the issues raised in the petition could not have been known while the petitioner was in-custody. The Antiterrorism and Effective Death Penalty Act of 1996 changed the procedures for issuing a certificate of appealability in federal court. Under the 1996 law, "there can be no appeal from a final order in a §2255 proceeding unless a circuit justice or judge issues a certificate of appealability." The United States Supreme Court held in Slack v. McDaniel, 529 U.S. 473, that the standard for issuing a certificate is whether "reasonable jurists could debate whether the petition should have been resolved in a different manner."
