Police officers have lost a High Court battle over Home Secretary Jacqui Smith's refusal to backdate their pay rise.
Jan Berry said the home secretary had breached police trust
Last month, police officers in England and Wales voted by an overwhelming majority to lobby the government for the right to strike.
What is the row over?
Last year Home Secretary Jacqui Smith decided not to backdate to September a 2.5% pay rise for police in England, Wales and Northern Ireland.
The police say this means their rise, only paid from December 2007, in reality amounts to 1.9% and that the Home Office has therefore breached an agreed deal.
In other words, the dispute is not over the increase set by the Police Arbitration Tribunal, but the manner in which the Home Office has decided to pay it.
What are officers paid at the moment?
Prior to this rise, new police constables began on £21,009. At the moment this could rise to £32,985, depending on length of service.
The pay increase sees all constables paid a minimum of £21,500, with those with the longest service receiving £33,800.
The Home Office says constables have seen a 36% wage increase since 1997, which is 10% above inflation.
Sergeants currently start on £32,985, and inspectors on £42,264.
Superintendents begin on £56,274, rising to £65,565 and chief superintendents have a starting salary of £67,200, rising to £71,031.
Why did the government decide to delay the Police pay rise?
Prime Minister Gordon Brown decided to stage public sector pay rises when he was still chancellor.
He said staging pay awards was an "essential part" of controlling inflation, keeping interest rates low and creating more jobs. He also said he would "do nothing" that he believed would put economic stability or low interest rates at risk.
However, officers in Scotland have had the full award as Scottish ministers have accepted the decision of the Police Arbitration Tribunal.
Can police strike?
No. The police are banned striking by an Act of Parliament. However, some members of the Police Federation are now calling for this ban to be removed because they say they are now being treated the same as other public sector workers - and should therefore have the same rights.
Can police take any form of protest action?
Thousands of police officers from across the country have organised a protest march in London over the issue. The Police Federation is also warning that it plans to ballot officers over whether they want to seek full industrial rights. That vote may happen in February.
Chris Herbert, editor of Police Review, said there were a few "fairly limited" ways in which the police could express their anger.
He said: "They could go back to their members to see if they wanted to take a ballot on whether they should have the right to strike or not.
"That could be the most high-profile, headline-grabbing thing they could do.
"Or they could withdraw their labour for voluntary posts or jobs that come up. Or they could do what's called working to minimum standards.
This would see officers following procedures "to the absolute minute, so it in a sense jams up the system, so that all the jobs they have to do would take a lot longer".
Is this dispute a one-off?
No, the row is part of a much larger dispute. Since 1980, pay has been set after talks in a special industrial relations body called the Police Negotiating Board.
The Police Federation supports the PNB, saying it provides a good negotiating environment with both sides around the table. Secondly, if the two sides fail to agree, the matter is referred to the independent Police Arbitration Tribunal for a binding decision.
There has been no dispute for years because both sides have abided by its rulings.
So what went wrong?
The Home Office said it wanted to replace this system with a pay review body closer to those in other areas of the public services, partly because of the need to keep public spending in check.
But the federation warned that such a body would ultimately ignore a principle of police pay - that they are no ordinary public servants. Ultimately a standard pay review body would not have the support of officers, it claimed.
The government's first move away from the old system went to arbitration after months of deadlock and ultimately led to the current crisis.
The home secretary has commissioned a further report into police pay. It is understood to recommend the public sector-style pay body that the government wants - but the detail has not yet been made public.
Chancellor of the Exchequer Alastair Darling has also floated the idea of three-year pay deals, similar to how other public sector spending is broadly set. Unions have not ruled it out - but are worried that living standards could slip if inflation were to outstrip the agreed awards.