The Parliament Act was invoked last night for only the fourth time since 1949. Political Editor Graham Dines outlines the nuclear option employed by MPs.

The Parliament Act was invoked last night for only the fourth time since 1949. Political Editor Graham Dines outlines the nuclear option employed by MPs.

WAR crimes prosecutions, the closed list proportional representation method for choosing Britain's European MPs, the lowering of the age for consensual gay sex to 16, and a ban on hunting with hounds have one thing in Common – they've all been forced onto the statute book using the Parliament Act.

It's the final option of the elected Commons to exert its authority over the unelected House of Lords.

The collective will of the people is expressed in their choice of Government. It cannot be thwarted by the objections of unelected peers.

All Bills have to be passed by both the House of Commons and the House of Lords before they can receive the Royal Assent and become law.

The Parliament Acts 1911 and 1949 defined the powers of the House of Lords in relation to legislation. Money Bills, primarily the Budget, always start life in the Commons and the 1911 Act ensured that the Lords no longer has the power to prevent taxation and revenue matters receiving the Royal Assent.

The Act was introduced after the Lords blocked David Lloyd George's People's Budget, which provided for pensions and health insurance for the working poor. This radical welfare reform was linked to a new land tax which so upset landowners in the Lords that they objected, and blocked the Budget.

Britain and King George V were faced with a major constitutional crisis, which was only resolved when the Liberal government threatened to create hundreds of peers to pack the upper house to vote through the Budget.

The 1911 Act also restricted the ability of peers to delay non-fiscal legislation to just two years.

That stayed the law until 1949. But the Lords' rejection of Clement Attila's government's plans for nationalisation of the steel industry saw the introduction of the second Parliament Act, which reduced the Lords' delaying powers to just one year.

Doubts have long been expressed about the validity of the 1949 legislation because the 1911 Act was used to force its successor on to the statute book. Unlike the 1911 Act, the later version was never agreed by the Lords.

Although the Lords can and often does raise objections to non-fiscal legislation, a compromise is usually reached or the upper house bows to the will of MPs.

In rare displays of defiance, the Lords can hold out for about a year. But ultimately the elected House of Commons can reintroduce it in the following session with identical wording and pass it without the Lords' consent.

What the Lords can do, and this cannot be overturned, is to stop a Government turning Britain into a totalitarian state by refusing to hold general elections at least every five years.

Such a course of action would need a special Act of Parliament, and if the Lords object and keep objecting then the Government could do nothing about it unless it packed the red benches of the upper chamber by creating hundreds of their supporters as life peers.

THE Acts have been used on just six occasions. Since 1949, the later Act had been used, until yesterday, three times: by John Major's Conservative government to put on to the statute book the War Crimes Act 1991, allowing prosecution of Nazis accused of murder in German-occupied Europe during the Second World War; and by Tony Blair's government to enact the Parliamentary Elections Act 1999, introducing a closed list system for choosing candidates, and the Sexual Offences (Amendment) Act 2000, which lowered the age of consent for homosexual acts to 16.

The process of the Parliament Act is an automatic one and requires no Government action or motion of the House of Commons. It is up to the Speaker to certify that a Bill falls within the scope of the Parliament Act 1949.

Yesterday, on the day the parliamentary session was prorogued, Michael Martin told MPs that the Hunting Bill having passed twice through the Commons within one year, and having been rejected by the Lords, was a suitable candidate for the Act and sent it to sovereign for her assent.

After a short delay, the Lord Chancellor Lord Falconer made a prorogation speech in the Upper House listing the measures Her Majesty's Government had enacted.

Included in that list was the Hunting Act and after its announcement, the Clerk to the Lords pronounced, in Norman French: "La Reyne le veult" - the Queen wills it.

Because no compromise could be agreed, hunting will be banned by the end of February. Whether that's the end of the affair seems highly unlikely.

Supporters of hunting and coursing are set to mount a legal challenge to the use of 1949 Parliament Act, claiming the Act is invalid because it was never itself passed by the House of Lords.

If that fails – and it may end up in the judicial section of the House of Lords as the court of final appeal before that itself is wound up and replaced by a Supreme Court – then the Human Rights Act may also be invoked by the hunters.

It could even end up in the European Court of Human Rights, where judges from across the Continent will be asked to rule whether it is lawful to infringe civil liberties by outlawing hunting.

As the majority of those who go hunting would seem to be naturally Eurosceptic, it would be a delicious irony if their cause was upheld by one of Europe's institutions.