Given the growth in the number of international treaties, there truly are fewer and fewer places where a criminal can now hide. Ronald Biggs, we hear you say, hasn’t he been cosily ensconced in Brazil for more years than he would have served in jail for his part in the Great Train Robbery? True, but even Brazil is getting in on the act, having last year negotiated an extradition treaty with Britain.

The post-war Nuremberg trials of Nazis made it clear to the world that war criminals should not be able to claim immunity from prosecution following the cessation of hostilities, confirmed by the United Nations in its Genocide Convention.

On September 11^th 1973, Chile’s Army Commander-in-Chief led Chile’s armed forces in a coup that overthrew the government of Salvador Allende, so ending the constitutional government in that South American country. Unfortunately for Allende, he resisted the army’s actions and fought to his death in the presidential palace. He was followed in the gilded halls by a military junta led by Pinochet, who assumed the Presidency and ruled for the next 17 years.

Who was Allende? Dr Salvador Allende was head of the Popular Unity coalition party, which combined the Socialists, Communists, Radicals and some Christian Democrats. When he won the presidency in 1970, he became the West’s first democratically elected Marxist leader. He nationalised the banks and various industries, including some U.S. interests (this would later attract the attention of many conspiracy theorists who claim, apparently with some historical justification, that the CIA trained and funded the Chilean military).

The Pinochet regime then engaged in torture, random arrests, summary executions and a campaign of terror that saw the disappearance of thousands. According to Amnesty International, over 250,000 citizens were detained just for political reasons. Pinochet abolished the National Congress, destroyed the voter rolls and generally repressed all opposition.

On 16 October 1998, during a visit to London to receive medical treatment, General Pinochet was arrested on the basis of a Spanish arrest warrant which alleged that Pinochet had been responsible for the murder of Spanish nationals in Chile at the time he was President.

Mr Nicholas Evans, a Metropolitan Magistrate, issued a warrant for the arrest of General Pinochet under section 8(b) of the Extradition Act 1989:

"…that between 11 September 1973 and 31 December 1981, within the jurisdiction of the National Court of Madrid, did murder Spanish citizens in Chile within the jurisdiction of the Government of Spain"

There were other allegations, as well, detailing "…the infliction of severe pain and suffering in the performance of his official duties...".

Extradition is a formal request by one government to another government to hand over a person suspected (or already convicted) of committing crimes in the petitioning country’s jurisdiction. Although we hear a lot of politicians rambling on about their efforts to secure the return of these alleged criminals, Christopher Skase is an obvious example, it is essentially a process carried through the courts, and so is a matter of law. And the long process involved in the Skase case (ironically being conducted in the country that has requested the extradition of Pinochet), and now the Pinochet case, allows rights of appeals from one court to another at every stage.

Let’s look at what "Jones on Extradition" says about the law of extradition. Before you can expect to have a realistic shot at gaining the extradition of the alleged criminal, you have to jump through more than a few legal hoops:

The arrest was first appealed to the High Court of England, which decided that Britain’s State Immunity Act gave immunity to "the sovereign or other head of State acting in his public capacity". The three judges decided that "acting in a public capacity" included the various allegations made about General Pinochet’s behaviour when he was in charge of Chile, despite the fact that this was fairly horrific.

This begs an obvious question – following this legal logic, would Hitler be immune from prosecution in Britain? Yes, according to Pinochet’s lawyers.

The prosecution argued that Pinochet’s actions, including "savage and barbarous crimes", are not within any legitimate functions of a head of State, and therefore the immunity given to foreign heads of state does not apply. Therefore, it was important to establish, in court, whether there were widespread violations of human rights in Chile during the military government.

This issue has been previously raised in the United States with regard to the notorious Ferdinand Marcos, former head of state of the Philippines, in the US Court of Appeals case of Hilao v Marcos.

It is said that whenever General Pinochet is in London, he brings flowers and chocolates for his old comrade, Baroness Thatcher. She has returned the favour – check out excerpts from her recent letter to the Sunday Times:

The House of Lords is both the upper house of the British parliament, and the Supreme Court of Appeal in Britain and Northern Ireland. Up till 1948, these appeals were heard in the chamber of the House, but are now heard by the Appellate Committee, which is usually made up of three to five Lords of Appeals (usually known as the "Law Lords").

The State prosecution appealed the decision of the High Court to grant immunity to Pinochet. The Law Lords made it clear that they had not been asked to decide whether General Pinochet should be investigated by a criminal court in Chile. If they had, the answer would obviously be yes. Instead, the question was a lot more tricky, whether General Pinochet was entitled to immunity as a former head of state from arrest and extradition concerning crimes allegedly committed at the time he was the head of state.

In a split 3-2 judgement, the House of Lords decide that Pinochet does not have immunity from prosecution, and so overturned the previous decision of the High Court to let him go home. Like their American judicial cousins, the Law Lords decided that acts of torture and hostage-taking stand outside the immunity afforded to a former head of state, because those actions cannot be regarded by international law as a function of a head of state.

The Law Lords were careful to confine their decision to the legal issues, and ignore the political realities. This is a good example of how the English, like Australia, have chosen to separate the functions of the judiciary and the State. Lord Nicholls put it well when he stated, at the end of his judgement, that: