From Scahill's Dirty Wars:

According to the National Security Act of 1947, the president is required to issue a finding before undertaking a covert action. The law states that the action must comply with US law and the Constitution. The presidential finding signed by Bush on September 17, 2001, was used to create a highly classified, secret program code-named Greystone. GST, as it was referred to in internal documents, would be an umbrella under which many of the most clandestine and legally questionable activities would be authorized and conducted in the early days of the Global War on Terror (GWOT). It relied on the administration’s interpretation of the AUMF passed by Congress, which declared any al Qaeda suspect anywhere in the world a legitimate target. In effect, the presidential finding declared all covert actions to be preauthorized and legal, which critics said violated the spirit of the National Security Act. Under GST, a series of compartmentalized programs were created that, together, effectively formed a global assassination and kidnap operation. Authority for targeted kills was radically streamlined. Such operations no longer needed direct presidential approval on a case-by-case basis. Black, the head of the Counterterrorism Center, could now directly order hits...

GST was also the vehicle for snatch operations, known as extraordinary renditions. Under GST, the CIA began coordinating with intelligence agencies in various countries to establish “Status of Forces” agreements to create secret prisons where detainees could be held, interrogated and kept away from the Red Cross, the US Congress and anything vaguely resembling a justice system. These agreements not only gave immunity to US government personnel, but to private contractors as well. The administration did not want to put terror suspects on trial, “because they would get lawyered up,” said Jose Rodriguez, who at the time ran the CIA’s Directorate of Operations, which was responsible for all of the “action” run by the Agency. “[O]ur job, first and foremost, is to obtain information.” To obtain that information, authorization was given to interrogators to use ghoulish, at times medieval, techniques on detainees, many of which were developed by studying the torture tactics of America’s enemies. The War Council lawyers issued a series of legal documents, later dubbed the “Torture Memos” by human rights and civil liberties organizations, that attempted to rationalize the tactics as necessary and something other than torture...

The CIA began secretly holding prisoners in Afghanistan on the edge of Bagram Airfield, which had been commandeered by US military forces. In the beginning, it was an ad hoc operation with prisoners stuffed into shipping containers. Eventually, it expanded to a handful of other discrete sites, among them an underground prison near the Kabul airport and an old brick factory north of Kabul. Doubling as a CIA substation, the factory became known as the “Salt Pit” and would be used to house prisoners, including those who had been snatched in other countries and brought to Afghanistan. CIA officials who worked on counterterrorism in the early days after 9/11 said that the idea for a network of secret prisons around the world was not initially a big-picture plan, but rather evolved as the scope of operations grew. The CIA had first looked into using naval vessels and remote islands—such as uninhabited islands dotting Lake Kariba in Zambia—as possible detention sites at which to interrogate suspected al Qaeda operatives. Eventually, the CIA would build up its own network of secret “black sites” in at least eight countries, including Thailand, Poland, Romania, Mauritania, Lithuania and Diego Garcia in the Indian Ocean. But in the beginning, lacking its own secret prisons, the Agency began funneling suspects to Egypt, Morocco and Jordan for interrogation. By using foreign intelligence services, prisoners could be freely tortured without any messy congressional inquiries.

In the early stages of the GST program, the Bush administration faced little obstruction from Congress. Democrats and Republicans alike gave tremendous latitude to the administration to prosecute its secret war. For its part, the White House at times refused to provide details of its covert operations to the relevant congressional oversight committees but met little protest for its reticence. The administration also unilaterally decided to reduce the elite Gang of Eight members of Congress to just four: the chairs and ranking members of the House and Senate intelligence committees. Those members are prohibited from discussing these briefings with anyone. In effect, it meant that Congress had no oversight of the GST program. And that was exactly how Cheney wanted it.