The Law Lords ruling on General Pinochet landed Home Secretary Jack Straw with one of the most difficult decisions he will ever have to take.

And, while his decision is on the face of it a purely legal one, politics will play a huge and probably decisive part in the proceedings.

If he allows the extradition requests from Spain he will be accused of the equivalent of handing Pinochet over to a lynch mob. Relations with Chile would certainly be damaged.

General Pinochet: Could yet be extradited and charged with genocide

But if he sends Pinochet back to Chile, he will still stand accused of letting him off the hook and relations with Spain will undoubtedly suffer.

The other arrest warrants from Switzerland, Belgium and France would then be activated.

Meanwhile, the Chileans are battling to heal the wounds left from Pinochet's reign and rebuild their country.

They have managed to forge a fragile accommodation with the past and Jack Straw has it in his hands to undermine that.

He's in a no-win situation.

The sensitivity of the situation explains why the Home Office is eager to point out that Mr Straw will be acting in a quasi-judicial role, with the right of appeal against his decision.

He will have to base his decision on whether or not to allow extradition on four principles:

• whether the alleged crimes are extraditable
• if the offences are political
• if there are issues of compassion to consider
• and the one that has historically proved the most problematic, whether the extradition papers are in order.

If he decided to allow the proceedings, things then get really complicated.

The case will return to the magistrates court for a decision on whether or not the General should be held in custody pending their decision on whether he should be extradited. He would be able to appeal against that decision.

If Mr Straw refuses the request, which would appear to fly in the face of the judges decision and it could force a judicial review into the entire affair. Either way the proceedings could drag on for years.

The Law Lords threw the problem into the home secretary's lap with a 3-2 majority verdict

The home secretary will also come under intense pressure from the competing campaigns in the affair, which paint a very different picture of the General's rule.

Few doubt that Pinochet ran one of the most vile regimes of the late 20th century, with tens of thousands of people allegedly butchered, tortured and "disappeared".

Their families say the suggestion he should be offered some sort of special treatment on compassionate grounds are an insult to the victims' memories.

Wasn't it Prime Minister Margaret Thatcher who insisted that Saddam Hussein should face a war crimes trial in the wake of the Gulf War and for his butchery of the Kurds.

Presumably, if Saddam was in ill health, that policy - doomed to failure thought it always was - would have been abandoned on compassionate grounds.

Margaret Thatcher: Prominent Pinochet defender

And Lady Thatcher's argument that Pinochet saved many British lives during the Falklands war smacks of the flawed notion that "my enemy's enemy must be my friend".

It also suggests that you can somehow balance the books of human evil.

Another argument, put with the usual force by Tory backbencher Teresa Gorman, runs that: "There are huge financial implications involved in this. Chile is a good friend of Britain and jobs and contracts could be put in jeopardy." It's an unattractive, but powerful argument.

And as ever, in the cold world of international politics, things are never black and white and the notion of national interest will rear its ugly head.