It has been impossible to have a grown-up debate on crime since Tony Blair became Shadow Home Secretary in 1992 and declared that Labour would be “tough on crime, tough on the causes of crime.” Since then, Labour’s policy has been to out-tough the Tories. The result has been a sentencing arms race as Labour and the Tories appeal to the most punitive parts of public and tabloid opinion.

We desperately need to shift the debate to what works to cut crime. That is why the Justice and Home Affairs Team have produced the Cutting Crime by Catching Criminals paper for our Autumn Conference. It sets out plans for a radical decentralisation, and a major shift in priorities towards measures that are shown by the international evidence to cut crime.

The Government’s own expensive research has shown that sentence severity has a negligible effect on crime. When only 1 in 100 crimes culminate in a conviction, posturing on penalties is pointless. It is the chance of getting caught that acts as a real deterrent to criminals. Catching more criminals is what works to cut crime.

That is why we focus on a significant shift in priorities away from prison towards policing. We are the only party to propose putting more police officers on the streets – 10,000 more, paid for by scrapping ID cards. Visible, neighbourhood policing is essential to good community relations, intelligence leads, and encouraging witnesses.

This is not just about more policing, but better policing. We propose a new National Crime Reduction Agency to assess the evidence on policing and criminal justice policy and to spread best practice. Even for the most serious crimes, detection rates vary wildly across the country. The clear up rate of violent crime, for example, is 67 per cent in North Yorkshire but just 36 per cent in the Met.

Even other comparable urban areas such as Greater Manchester and Merseyside have detection rates for violent crime of more than 50 per cent. Improving the national average detection rate to the rate of the top 10 per cent of forces would see 400,000 more crimes solved, including 140,000 violent crimes.

Unlike Labour and the Tories, we will not duck the big issues in police reform. Some of the most restrictive working practices in the police have gone unchanged for decades. We will urgently review the single point of entry; the 30 year lifetime career; and the determination of pay by seniority instead of talent and effort. It is unfair on the vast majority of diligent and hard-working officers that less conscientious colleagues are not tackled.

At the heart of our proposed reforms is a radical decentralisation of power in line with the public services commission ideas in the last parliament. Police authorities will hold chief officers to account (including sacking them if necessary); set local priorities instead of following counter-productive Home Office targets; and set budgets and precepts without capping. Local powers are essential in the public services if there is to be experiment and innovation: good practice will be copied, and failure shunned.

However, if we are to give police authorities greater unfettered powers, the electorate must be able to hold the majority of their representatives directly to account. There is a time-honoured liberal tradition of no taxation without representation. Police authorities need the mandate to resist Home Office centralisation and set budgets and precepts.

Of course, councils should be the focus of local accountability wherever possible. That is why we propose that councils should act as police authorities whenever police forces have the same borders as councils. But many forces have now been merged, and there is no appetite for another upheaval. So where forces straddle many different councils – 14 for example in Hampshire – we need other solutions.

Part of the solution is to align police command units with local councils to improve dialogue and accountability. Councils can make an enormous difference to crime-fighting, as our own successes in Liverpool and Newcastle have shown. But you cannot have a chief constable accountable to all the councils in his or her area, as that would be a recipe for chaos.

So for the 35 police authorities that straddle lots of councils (out of the total number of 43 in England and Wales), we propose that two thirds of their members are directly elected by fair votes (single transferable vote). One third would continue to be nominated from councils. Authorities would also be able to co-opt other members, like magistrates, to ensure diversity and expertise.

Unlike Labour and Tory plans for elected sheriffs, our proposals ensure that all groups and opinions, including women and ethnic minorities, would be fairly represented. Elections would be about policing issues, not populist posturing. These plans also breathe life into our commitment to localism by ensuring that councils take control where possible, but that police authorities are fairly elected otherwise. And they set out a route march for a real attack on crime by focussing not on what sounds tough, but on what works.

Chris Huhne is the Shadow Home Secretary.