It cost £60m to create. Its annual running costs are expected to be £12.3m. And it replaces something that has been running perfectly well for more than 100 years.

It’s the UK Supreme Court, which opens for business on 1 October. The new court assumes the role of the Law Lords, or the appellate committee, who sat in the House of Lords for the last time after 133 years on 30 July. The Law Lords will now be known as Justices of the Supreme Court which, there’s a clue in its title, is to be the highest court in the land.

The great and the good of the legal world – there were high-ranking delegates from Europe, Africa, Asia, Australia, New Zealand and the Americas – came together at King’s College, London, last week to mark the beginning of the new era. They were there to discuss freedom of expression and the role of a supreme court.

Security was tight, such that the legal correspondent of a leading quality newspaper, who had forgotten her invitation, had to blag her way in. The reason for the security, it transpired, was the presence of one John G Roberts, Jr – the chief justice of the United States of America.

Lady Justice Arden kicked off proceedings with an overview of the function of supreme courts around the world. They are final courts of appeal, she said, and have a leadership role in setting out how the law should develop. The UK version will also have the power to determine devolution questions.

On freedom of expression, she touched upon the media’s part in exposing how MPs have taken advantage of their, some would say, overly liberal expenses regime. The media also recently brought to light a plan to tar opposition politicians with invented scandals. Such press freedom brought with it responsibilities, however, such as the right to privacy for supermodel Naomi Campbell.

A panel discussion ensued chaired by Lord Phillips of Worth Matravers, president-elect of the UK Supreme Court.

John G Roberts, Jr said a supreme court should ignore public opinion and focus on its constitutional duty, which was often to interpret a written constitution (not an issue likely to exercise the UK Supreme Court). He added he was proud to live in a country that recognised an individual’s right to protest by burning the national flag.

Kate O’Regan, a South African judge and chairwoman of the Internal Justice Council of the United Nations, said a supreme court should show leadership. ‘It can’t run with the ball, but must lead on constitutional issues as they arise.’

Lieutenant governor and chief justice of New South Wales James Spigelman said: ‘Freedom of speech doesn’t extend to the right to shout "Fire!" in a crowded theatre. It is often a question of balancing two contrasting rights – freedom of expression and privacy.’

There followed questions from the floor. Should people have the right to ‘hate speech’? Does the impossibility of controlling the internet threaten the jury system – because how can you ensure jurors are not ‘Googling’ a defendant to see if he has previous convictions? Still on the internet, what about electronically filing bankruptcies, which often contain details of national insurance numbers, addresses, bank details and so forth?

Lord Phillips closed the debate with an eloquent swipe at the media. ‘Freedom of speech must be measured against the public interest. There is a distinction between public interest and what the public is interested in – not a distinction the press always draws.’