The Military Commissions Act of 2006 (MCA) marked the high tide and endgame for hiding torture. It's unraveling did more to uncover the Bush administration's secret interrogation practices than did the political change in Washington. International and domestic backlash against the government's embrace of harsh interrogation techniques, frequently rising to the level of torture, also played a role. However, the Supreme Court's decisions ending in Boumediene v. Bush played the decisive role. Boumediene, and the Supreme Court decisions that led up to it, made inevitable that which politics had left contingent and reversible. It also provided legal and political cover.
Alan W. Clarke,
De-cloaking Torture: Boumediene and the Military Commissions Act,
San Diego Int'l L.J.
Available at: https://digital.sandiego.edu/ilj/vol11/iss1/5