Protecting Classified Information and the Rights of Criminal Defendants: The Classified Information Procedures Act [Updated August 31, 2016] [open pdf - 937KB]
From the Summary: "A criminal prosecution involving classified information may cause tension between the government's interest in protecting classified information and the criminal defendant's right to a constitutionally valid trial. In some cases, a defendant may threaten to disclose classified information in an effort to gain leverage. Concerns about this practice, referred to as 'graymail,' led the 96th Congress to enact the Classified Information Procedures Act (CIPA) to provide uniform procedures for prosecutions involving classified information. Examples of recent cases implicating CIPA have arisen in the context of prosecutions against alleged terrorists, as well as prosecutions involving the unauthorized disclosure of classified information by former intelligence officials."
CRS Report for Congress, R41742
Congressional Research Service: https://crsreports.congress.gov/