Judges who preside over the highest court in the land will become Justices of the Supreme Court today, losing their time-honoured tenure of the House of Lords.
They will be sworn in at a ceremony when the new Supreme Court of the United Kingdom comes into existence, replacing the Appellate Committee of the House of Lords.
It will mark a landmark moment in constitutional and legal development, separating Parliament from the judiciary at its highest level.
But some lawyers believe it is also a giant step towards creating an elected House of Lords.
Paul Stone, senior partner with solicitors DLA Piper, said although the creation of the Supreme Court will move the Law Lords out of the House of Lords in legal terms it will not change much apart from where they sit.
"The fear that their distance from the House may lead to issues like those in the United States where independence allows them demonstrably to flex their muscles is not supported by enough compelling evidence to suggest it is actually a risk.
"Of greater significance - and something that has been largely overlooked - is that moving the Law Lords out of the House of Lords will mean that their input into Parliamentary Committees and the scrutiny and perspective they bring may be lost.
"Furthermore, moving the Law Lords out of the House would remove one of the major barricades to creating an elected House of Lords, which Jack Straw is keen on doing.
"So, the creation of a new Supreme Court could be less about a change in the way our legal system operates and more about a potential shift towards a massive change in our Parliamentary structure."
The new home of the Supreme Court is the former Middlesex Guildhall, on Parliament Square. It has been painstakingly renovated over the past two years but many original features have been restored and brought back to full splendour.
Established through the Constitutional Reform Act 2005, the Supreme Court will hear civil appeal cases from England, Wales, Northern Ireland and Scotland, as well as criminal appeal cases from England, Wales and Northern Ireland.
It takes over the devolution jurisdiction of the Judicial Committee of the Privy Council (JCPC). The JCPC continues to be the final court of appeal for certain Commonwealth countries and other jurisdictions, such as Crown Dependencies.
For the first time at any court in the United Kingdom, proceedings will be routinely filmed and made available to broadcasters.
The building is open to the public during working hours.
Following the swearing in this morning, the Justices will take part in the annual procession in their robes to Westminster Abbey to attend the annual service that marks the start of the new legal year in England and Wales.
They will be joined by judges from the Royal Courts of Justice in The Strand and will then attend the Lord Chancellor's breakfast in the Great Hall in the Houses of Parliament.
Lord Phillips of Worth Matravers, president of the Supreme Court, said: "For the first time, we have a clear separation of powers between the legislature, the judiciary and the executive in the United Kingdom. This is important. It emphasises the independence of the judiciary, clearly separating those who make the law from those who administer it.
"As Justices of the Supreme Court we will be more visible to the public than we ever were when sitting as members of the House of Lords. This is desirable as the court will only decide points of law of public importance.
"Justice at the highest level should be transparent and the new Court will have a crucial role in letting the public see how justice is done."
Jenny Rowe, chief executive of the Supreme Court, said: "The establishment of the Supreme Court is an important historic moment.
"The improvements and modernisation that this brings creates exciting new opportunities to show the wider public how justice is done at the highest level, to increase awareness of the UK's legal systems and the impact the law has on people's lives."