The indefatigable data-miners over at Cryptome have dug up the genesis of the special access projects the Bush administration has used to wage the war on terror, projects including the interrogation of suspected terrorists.
It's mostly in dense, purposely coma-inducing governmentese, but the upshot is the SAPs provided a channel to skirt Congressional oversight, at least temporarily, of a host of secret endeavors. Or in the original, "The establishment of a SAP will be based on a determination that normal security protections are not adequate based on the threat and/or vulnerability or the information to be protected, and that enhanced security protections are required."
What of things could be grounds for a SAP? Just about anything, including: "Extremely sensitive activities conducted in support of national foreign policy objectives abroad, which are planned and executed so that the role of the U.S. Government is not apparent or acknowledged publicly."