It was a medical drama from the start. The arrest and prosecution of Augusto Pinochet for the international crime of mass torture began in a London hospital in October 1998, where the former dictator was seeking treatment for a bad back.
Fifteen months later, the case has ended on a medical whimper. Gen Pinochet has been held on a Spanish extradition warrant charging him with the torture and murder of several thousand members of the Chilean left, including Spanish citizens. But four British specialists have notified Jack Straw, home secretary, that the 84-year-old former head of state is too frail and medically unfit to stand trial.
Gen Pinochet will probably be allowed to live out his days in Santiago. There will be no Chilean prisoner in a Spanish dock. The attempt by Baltazar Garzon, the Spanish magistrate, to try the unrepentant coup leader for his violent purges has come to naught. Or has it? The 15-month saga has brought about significant changes in human rights law and in Chilean politics.
Gen Pinochet is the first former head of state to be arrested by the authorities of another state, at least in modern times. Germany's Kaiser escaped the Allies in the first world world, when the Dutch refused to extradite him. The Nuremberg tribunal was limited to Hitler's henchmen, and General Douglas MacArthur remarked that he did not dare try Emperor Hirohito without calling up another million American soldiers for the occupation of Japan. General Manuel Noriega was convicted in a US court on narcotics charges, but the US denied that he was Panama's rightful head of state after the rigged 1989 elections and sent 26,000 men to replace his regime.
Ten of the 15 British judges who ruled on Pinochet's case over the months of hearings and appeals, including the Law Lords, recognised two key changes in international law that would permit future cases against rogue leaders.
First, foreign torture can now be tried as a crime in countries across the globe under the legal innovation of "universal jurisdiction". At least 110 countries have ratified the 1984 United Nations Convention on Torture. It creates a system of hue and cry - any country that finds a perpetrator in its midst is legally bound to try or extradite him. Signatories include Britain, Spain, the US and even Chile, which ratified the convention in 1988.
The British judges limited their ruling to crimes occurring after December 1988, when British courts obtained jurisdiction over extraterritorial cases. But for the future, the system is in place. International thugs contemplating air travel through Heathrow must be concerned.
Second, former dictators can no longer claim sovereign immunity by arguing that their violation of human rights law was an "official act". Sitting heads of state still cannot be arrested, and nor can ambassadors (to allow foreign diplomacy to continue), but a former head of state or cabinet official will not be able to waltz away.
These less essential personnel do not enjoy absolute immunity, but only a narrower immunity for acts that fall within their duties. The House of Lords' decision on Gen Pinochet newly declares the limits of those duties. No local law, constitution or military decree can legitimise the international crime of torture and place it within a job description.
In the old days, the only question a court asked was whether violence had a public or a private aim. Now, a campaign of torture is declared to be unfit for the company of truly public acts.
The British precedent has its limits. The liability of former heads of state will not necessarily extend to a single act of torture. And, because heads of state often do not step down until they are old and ailing, it is more likely to be the police chiefs and interior ministers who are caught. But the end of international back scratching (lawyers call it "comity") is revolutionary, nonetheless.
The second change is in Chilean politics. When Gen Pinochet stepped down from power in 1990, he became a "senator for life" with parliamentary immunity from arrest. In the first civilian government in Chile, President Patricio Aylwin, even as a Christian Democrat, could not get an assembly vote for a truth commission, establishing it by executive act instead.
Nonetheless, in the glare of the London proceedings, Chile's judiciary has become more daring. A Chilean judge is considering the withdrawal of Gen Pinochet's parliamentary immunity. Just as Argentina's courts now give a narrower reading to military amnesties, so too Chile has transferred some cases from military courts to civilian tribunals.
Gen Pinochet was undoubtedly surprised that the aid he gave London during the Falklands conflict in 1982 did not curtail Britain's willingness to consider the Spanish request for prosecution. British adventurousness may encourage some local judges to take a chance as well.
The author is a senior fellow at the Council on Foreign Relations, and a professor of law at Yale university.