You can often tell if someone understands how wrong their actions are by the lengths to which they go to rationalize them. It took 81 pages of twisted legal reasoning to justify President Bush’s decision to ignore federal law and international treaties and authorize the abuse and torture of prisoners.

Eighty-one spine-crawling pages in a memo that might have been unearthed from the dusty archives of some authoritarian regime and has no place in the annals of the United States. It is must reading for anyone who still doubts whether the abuse of prisoners were rogue acts rather than calculated policy.

The March 14, 2003, memo was written by John C. Yoo, then a lawyer for the Justice Department. He earlier helped draft a memo that redefined torture to justify repugnant, clearly illegal acts against Al Qaeda and Taliban prisoners.

The purpose of the March 14 memo was equally insidious: to make sure that the policy makers who authorized those acts, or the subordinates who carried out the orders, were not convicted of any crime. The list of laws that Mr. Yoo’s memo sought to circumvent is long: federal laws against assault, maiming, interstate stalking, war crimes and torture; international laws against torture and cruel, inhuman or degrading treatment; and the Geneva Conventions.