A U.S. Truth Commission - NYTimes.com Re "World Bids Farewell in the Land Mandela Freed" (news article, Dec. 11): President Obama remarked in his eulogy to Nelson Mandela, "Reconciliation is not a matter of ignoring a cruel past, but a means of confronting it with inclusion and generosity and truth." The president should heed his own words and convene a federal truth commission examining our nation's shameful and dangerous use of torture after the Sept. 11, 2001, terrorist attacks. When Senator Patrick Leahy proposed such a commission in 2009, the president opposed it. Therefore, much remains unknown about how our country systematically implemented torture and how to prevent it from happening again. Nelson Mandela understood the danger of such ignorance. In 1994 he called for a truth commission on apartheid and not simply its dismantling. "What this issue raises," he said, "is how we deal with a past that contained gross violations of human rights - a past which threatens to live with us as a festering sore." A comprehensive federal truth commission on American torture remains a moral and national security imperative. President Obama ignores Mr. Mandela's cautionary words at our nation's peril. The writers are, respectively, director and policy coordinator of the Bellevue/N.Y.U. Program for Survivors of Torture.