Such a person is to be investigated, and if the facts warrant, must either be prosecuted for the crime of torture or extradited to another country that will prosecute.
The convention intends to avoid impunity for this most serious of international crimes by removing the possibility that the torturer will be able to find any safe haven. This was the basis for Pinochet's arrest in Britain.
The potential problem for Yoo, vice presidential chief of staff David Addington and others who may have been associated with torture, is to be found in Article 4 of the convention. This section criminalizes not only the act of torture itself but also other acts, including "an act by any person which constitutes complicity or participation in torture."
Can the mere drafting of legal advice that authorizes a policy of torture amount to complicity in torture?
Any case will turn on its particular facts. A prosecutor would have to establish that there was a direct causal connection between the legal advice and the carrying out of particular acts of torture, or perhaps a clear relationship between the legal advice and a governmental policy that permitted torture (or turned a blind eye to it).
That evidence is not yet established, and it would be inappropriate to prejudge the outcome of any investigations that may be carried out in the future.
Nevertheless, those associated with the legal opinions and their surrounding policies should be aware that there is case law from Nuremberg that suggests that lawyers and policymakers can be criminally liable for the advice they have given and the decisions they have taken.
In the case of United States vs. Josef Altstotter, some of the accused were lawyers who had been involved in enacting and enforcing Nazi laws and Hitler decrees that permitted crimes against humanity. None of the defendants was charged with murder or the abuse of a particular person. They were charged with participating in a governmentally organized system of cruelty. As the tribunal put it: "The dagger of the assassin was concealed beneath the robe of the jurist." Eight of the 14 were convicted in December 1947 for "complicity in international crime."
It is not just lawyers who should beware. Some media reports have suggested that a chief architect of the policy that gave rise to the legal advice was Addington, who has recently been appointed as the vice president's chief of staff, after Lewis Libby's indictment and resignation.
If Addington did play such a role, and if further evidence emerges that acts of torture resulted from the existence of any such policy, then he too may wish to reflect carefully before embarking on foreign travels.
Responsibility may go even higher in the administration's hierarchy.
These are early days in understanding the precise relationship between the administration's policy on detainee interrogations, the legal advice and the allegations of abuse at Guantanamo, Abu Ghraib and elsewhere.
There is a need for a full and independent investigation. There is an urgent need to bring into law Sen. John McCain's sensible and welcome proposal to explicitly ban abusive treatment and give effect to the United States' obligations under the torture convention.
In the meantime, the Pinochet and Altstotter cases and the torture convention should serve as a salutary reminder of the growing reach of international criminal law.
The possibility cannot be excluded that the Pinochet precedent will come back to haunt Addington, Yoo and others in the Bush administration. International law is not just for other people in other countries. Ignoring it will not be cost-free, including worries about foreign travel, as former Peruvian president Alberto Fujimori learned last week when he was taken into custody in Chile.
This article first appeared in the San Francisco Chronicle (www.sfgate.com).