Police officers were given permission yesterday to launch a High Court challenge over a Government decision effectively limiting this year's pay award to 1.9 per cent.
A judge said he had "no hesitation" in finding they had an arguable case to bring an urgent application for judicial review.
Police Federation lawyers say forces around the country had a "legitimate expectation" that they would receive the full 2.5 per cent increase recommended by an independent arbitration tribunal.
Home Secretary Jacqui Smith (Redditch) decided in December not to back-date the 2.5 per cent award recommended by the pay tribunal to September 1, the beginning of the police pay year, leading to the reduced increase of only 1.9 per cent.
More than 22,000 off-duty officers marched through Westminster last month to protest about the pay deal in the biggest gathering of police officers in Britain's history. Every force in England and Wales was represented.
The offer was backdated for officers in Scotland but not in the rest of the UK. The West Midlands Police Authority had previously said it was willing to meet the offer in full.
John Francis, general secretary of the Police Federation, welcomed Mr Justice Collins' decision yesterday.
He said: "This is an opportunity to challenge the betrayal of the Home Secretary in failing to make an award in line with the police arbitration tribunal.
"Last month, some 25,000 police officers demonstrated peacefully in central London.
"But this doesn't disguise the anger that is felt out there at the way they have been betrayed by the Home Secretary.
"The court is probably the last avenue left open to us."
Mr Justice Collins was told by lawyers for both sides that the Home Secretary was not opposing the fact that the police case was arguable, but it was for the judge to decide whether to grant permission.
Giving the go-ahead, the judge said: "I don't think I would have had any hesitation granting permission."
He ordered that the case should come on for a full hearing over two days and provisionally earmarked it for April 15-16.
The challenge is formally being brought in the name of the staff side of the Police Negotiating Board (PNB).
The Police Federation is being joined by police superintendents and chief police officers in mounting the legal action.
A petition was handed in to 10 Downing Street signed by more than 40,000 people supporting the campaign for a better pay settlement.
The Prime Minister was challenged over the increasingly bitter dispute at Prime Minister's Questions.
Gordon Brown told MPs that he would have "liked" to have given the police more money but had to keep a check on inflation.
By not back-dating the increase, the Government has brought it within its two per cent public sector pay limit.
David Davis, the shadow Home Secretary, has accused the Government of "a betrayal of trust".
The Police Federation, which is at the centre of today's challenge, claims that Ms Smith had no power to overrule the pay tribunal unless it was necessary for reasons of "utmost national importance".
Ms Smith had also "approached the negotiations with a closed mind and had no intention of accepting any award that did not produce a figure for 2007 of less than two per cent".
Another ground of challenge will be that Ms Smith's decision was "procedurally defective" and was an "abuse of the PNB process" by failing to tell the federation before announcing her decision.
The action also claims that officers' human rights are being infringed - in this case a right to freedom of association - because the police have given up the right to strike over pay.
Federation chairman Jan Berry said: "This is a positive step for the 140,000 police officers across England and Wales in their fight for fair pay."