From the wikiedia entry on torture:
On December 10, 1948 the United Nations General Assembly adopted the Universal Declaration of Human Rights (UDHR). Article 5 states, “No one shall be subjected to torture or to cruel, inhuman or degrading treatment or punishment.” Since that time a number of other international treaties have been adopted to prevent the use of torture. Two of these are the United Nations Convention Against Torture and for international conflicts the Geneva Conventions III and IV.
It is hard to argue against the UDHR at least without ridiculous mental gymnastics which result in logic which can never be universally applied.
Therefore, however noble or pragmatic Obama’s intentions, executive orders are inappropriate for governing torture.
Finally, one can apply Obama’s “looking forward and not backward” to argue against the Nuremberg Trials. When bank robbers are caught, we don’t just take the money and move on. They are tried for bank robbery. When Saddam was deposed in Iraq, a search for him commenced in order to bring him to justice. Obama’s stance is not only weak here, it is inappropriate. The only way to move forward is to bring criminals to justice.