After a death sentence is affirmed in state collateral review, the prisoner may file for <answer>federal</answer> habeas corpus, which is a unique type of lawsuit that can be brought in <answer>federal</answer> courts. Federal habeas corpus is a species of collateral review, and it is the only way that state prisoners may attack a death sentence in <answer>federal</answer> court (other than petitions for certiorari to the United States Supreme Court after both direct review and state collateral review). The scope of <answer>federal</answer> habeas corpus is governed by the Antiterrorism and Effective Death Penalty Act of 1996, which restricted significantly its previous scope. The purpose of <answer>federal</answer> habeas corpus is to ensure that state courts, through the process of direct review and state collateral review, have done at least a reasonable job in protecting the prisoner's <answer>federal</answer> constitutional rights. Prisoners may also use <answer>federal</answer> habeas corpus suits to bring forth new evidence that they are innocent of the crime, though to be a valid defense at this late stage in the process, evidence of innocence must be truly compelling.
In what courts can federal habeas corpus suits be brought?
federal