BBC Legal Affairs Correspondent Jon Silverman: "This should make for swifter justice"

Unveiling the plans, Home Secretary Jack Straw said he intends to stop people accused of theft, burglary and assault from opting to be tried in a crown court, rather than by magistrates.

The move would restrict the historic right to a trial by jury for around 18,500 defendants in England and Wales a year.

The move has been criticised by the Conservatives, Liberal Democrats and some Labour MPs but is being backed by the Police Federation.

The government believes its plans would "curtail abuse of the system" and cut costs.

'Fair and just'

Jury trials cost on average £13,500, compared with only £2,500 for a case tried by magistrates

But director of the civil rights group Liberty, John Wadham said Mr Straw's proposals were "fundamentally flawed".

Speaking on BBC Two's Newsnight programme he said defects within the criminal justice system could not be "remedied by taking away people's rights", he added that taking rights away simply to save money was wrong.

Jack Straw: Changed his mind on trial by jury

The home secretary unveiled the move during a speech to the Police Federation Conference in Blackpool on Wednesday.

He said: "The primary aim of our justice system is to be fair and just - and the rights of the defendant must be paramount.

"But we also have a responsibility to ensure that those rights are not abused.

The BBC's Nigel Doran: "Jack Straw will have to brush off disapproval from his critics"

"It has long been a source of irritation to police officers and others, that defendants in many cases are 'working the system' by demanding crown court trial for no good reason other than to delay proceedings."

The move will affect defendants in so-called "either way" trials, which can be dealt with in either a crown court or a magistrates' court.

While serious crimes such as murder, rape and arson can only be tried by a jury, many offences can be heard in either court.

Currently, it is up to defendants to opt for trial by magistrates - two or three justices of the peace - or by judge and jury.

Jack Straw: "This right does not go back to the Magna Carta...and it has been abused"

The home secretary fought against similar changes to the system when he was in opposition.

As shadow home secretary, Mr Straw told Parliament: "Surely, cutting down the right to jury trial, making the system less fair, is not only wrong but shortsighted, and likely to prove ineffective."

But on Wednesday he said: "In changing my mind, we have actually changed the proposal to deal with one of the major objections to the initial proposal, which was that there was going to be no appeal at all from the magistrates' refusal of jurisdiction.

"The only way round that would be a substantive appeal against conviction or a judicial review to the divisional court.

"We are dealing with that directly by putting in the right of appeal, an interlocutory right of appeal, a straightforward one, to a crown court judge."

Better chance of acquittal

The Home Office says defendants often elect for trial by jury only to end up pleading guilty anyway.

Bruce Holder, QC, chairman of the Bar Council's public affairs group, criticises Mr Straw's U-turn

But those who proceed have a higher chance of winning their case. About 40% of people pleading not guilty are cleared in the crown court, compared with just 25% appearing before magistrates.

The Bar Council says black people will be particularly badly hit by the reforms.

Research has shown black people are more likely to opt for jury trials, as they often have little confidence in magistrates' impartiality.

Malcolm Fowler, of the Law Society, says the changes would introduce an element of "class justice"

A Law Society spokesman said: "We strongly oppose any move to take away a defendant's right to chose to be dealt with by a jury when being tried for an offence which can have serious consequences on conviction."

Speaking for the Society of Black Lawyers, Courtenay Griffiths QC criticised the proposals in the wake of the inquiry into the murder of black teenager Stephen Lawrence, which, he said damaged the credibility of the police.

"The evidence is that black defendants see magistrates courts as police courts.

"A fair hearing from a randomly selected panel of jurors greatly enhances the confidence that minority communities have in the justice system."

MPs' anger

The home secretary's plans also provoked strong words in the Commons.

Mr Straw's Tory shadow Sir Norman Fowler was angered by the home secretary's failure to announce the plans in the House.

Labour MP Chris Mullin also pointed out that there may be many good reasons for defendants electing crown court trial rather than face magistrates.

Tory home affairs spokesman James Clappison said: "Trial by jury is a very important part of our constitutional fabric which Labour now seems intent on tearing apart."