Britain?s highest court will hear a test challenge today that to extradite a retired businessman to the United States would be a breach of his human rights.

Ian Norris, 66, former chief executive of Morgan Crucible, has lodged a last-ditch appeal against being extradited over allegations dating back ten years that he obstructed the course of justice.

The case, to be heard heard by nine Supreme Court justices, headed by Lord Phillips of Worth Matravers, the court?s president, is being keenly watched by MPs, civil libertarians and others as a test of extradition laws with the United States.

But it could also provide a last glimmer of hope for Gary McKinnon, the computer hacker whose case the Home Secretary finally rejected on Thursday night.

Alan Johnson dismissed claims by Mr McKinnon?s lawyers that extraditing the Asperger?s sufferer would breach his human rights despite medical evidence indicating that Mr McKinnon is likely to kill himself if extradited.

Mr McKinnon, 43, how has seven days in which to appeal.

In Mr Norris?s case his legal team will argue that extradition would breach article eight of the Human Rights Act, his right to a private and family life.

Mr Norris, who is in ill health, has already won a partial victory over extradition when he took his case all the way to the House of Lords and they said that he could not be extradited on the main allegations of price-fixing.

In March 2008 they ruled that price-fixing was not a criminal offence in England at the relevant time and therefore not an extradition offence under the Extradition Act 2003.

However the ruling left open the prospect of extradition to face charges of obstructing the course of justice - which Mr Norris strongly denies.

Yesterday, his lawyer, Alistair Graham, a partner with the international law firm White & Case, said: ?A person?s right to a private life can be interfered with - but only where that is proportionate in the interests of national security and for the protection and prevention of crime.

?It is a balancing act. And we say that to extradite him for this subsidiary charge when the law lords have already knocked the stuffing out of the case is disproportionate and a breach of his human rights.?

Liberty, the human rights group, is also making a legal intervention in the case in support of Mr Norris?s case.

His QC, the leading silk Jonathan Sumption, will argue that the investigation allegedly obstructed by Mr Norris was not an investigation into anything that was regarded as criminal at the time in England.

He will also argue that the couple?s family life would be completely broken and their enforced separation effectively permanent because of their health and uncertain life span.

Mr Norris, who is now retired, lives with is wife Sheila in Maidenhead, Berkshire, and his been fighting extradition for more than six years.

He worked with the carbons division of Morgan Crucible for 29 years and became its chief executive in 1998, with responsiblity for 180 subsidiaries in more than 60 countries.

He retired on health grounds in 2002 and is suffering from prostrate cancer. His 65-year old wife, meanwhile, is struggling with severe depression.

He told The Times: ?This appeal is our last hope but I have always had every faith in British justice. It is a very tense time, as you can imagine.?

Of the battle against extradition he said: ?It feels like a lifetime. And it has been especially difficult for my wife.?

In the last year alone he has had two operations: a second knee replacement and a hip replacement.

Mr Graham added: ?Ian is stoically dealing with all this and hopding up pretty well. But it has had a real impact on his wife.?

It is alleged that between 1999 and 2001 Mr Norris authorised the removal or destruction of documents containing evidence of price-fixing from the files of Morgan Crucible companies in Europe; directed a company employee to do likewis in the United States and that at various meetings in England he agreed with company employees that they would give false accounts to Department of Justice investigators at meetings where price-fixing had been discussed.

He has always denied the allegations. His lawyers will say that the absence of any obligation by the States to private a prima facie case and the fact that Mr Norris is not entitled at this stage to the particulars of evidence against him make it difficult to assess the strength of the prosecution case.