For all those know-alls on the Labour benches (and there are quite a few) who say that issues such as devolution and Lords reform are airy-fairy nonsense, the next couple of weeks will bring a rude and timely shock. Few issues matter more to their constituents "in the real world" than decent policing. For the activists, banning fox-hunting remains almost equal as a passion-stirrer. Yet, on both, the government is going to hit the great blockade, again: the House of Lords.

David Blunkett's Police Reform Bill is the really important measure. Like most Home Office bills, all sorts of things are in it, from allowing traffic wardens to stop cars to measures that encourage new community safety schemes.

But the controversial core is that it gives him, as Home Secretary, huge new powers over local police forces, including the ability to "direct" police authorities and to seek the retirement or resignation of a chief constable "in the interests of efficiency or effectiveness". Along with his new National Policing Plan, these powers give Blunkett an authority none of his many famous predecessors has had.

I say "give", but "would give" is more accurate. The ordinary punter, worried about rising street crime, wondering where the police get to these days, might have assumed that the man nominally in charge of the police, the Home Secretary, really was in charge of them. But constitutional traditionalists know better.

The local nature of British policing, and the independence of the chief constables, which makes them more like barons of Plantagenet England than servants of the state - these are supposed to be among the glories of the realm.

As Simon Jenkins wrote in his book Accountable to None, the key to policing by consent in Britain is that the police are not answerable to the state, as in France: "Together with lack of weapons and non-military uniforms it has made British police forces famous for their popularity." A police officer's job was to enforce Westminster laws, "but he does so always with a glance over his shoulder to his local community".

In fact, police localism has been encroached on throughout modern times, notably in the 1960s and then again in the Thatcher-Major years. But what police chief constables have still had up until now was independence to enforce the law in their own style.

It is this that Blunkett now threatens. The House of Lords, bastion of tradition even on the edge of its own destruction, hates all this. The Tory peers are making common cause with the Liberal Democrats and many crossbenchers. As with fox-hunting, they can easily defeat the Labour view from the Commons. On fox-hunting, the peers may flinch, recognising the danger of a head-on confrontation with the popular will. But on the Police Reform Bill, they will stand and fight. They will defeat Blunkett, setting the scene for another Lords-Commons fight.

This time, however, because the bill started in the Lords, the government will not be able to use the Parliament Act to push it through - which looks to me like a bit of a blunder. Blunkett's instinct is dangerous, but right - and should be supported by all Labour MPs. It is dangerous, first, because the more that central government takes on all responsibility for local policing, the more failures will be laid directly at the door of the Home Office. This is something the Health team has learnt, which is partly why it is desperately trying to decentralise and devolve power in the NHS.

And it is also dangerous because we need experiments in public policy in this country - the aggressive street-policing advocates in the north of England, for example, should not be stamped on or made to conform to some civil service norm.

How else will we find out what works? We don't want a Home Secretary slapping down every new experiment. And there is a danger of that in this bill.

But on balance, for two bigger reasons, this is the right thing to do. The first is the ludicrous situation where the government is judged on the performance of local police forces without the full powers to influence them. It is an act of some political courage to acknowledge responsibility and seek more of it.

Policing is changing unavoidably - more guns, more technology, more violence - and a progressive government needs to have a grip. Dixon of Dock Green died decades ago. And here comes the unpopular bit: Blunkett is also right because he needs to take on the police, something that will cause a terrible storm in parliament and the press, but which cannot be ducked any longer.

Yes, policing can be a hard and dangerous job - with those guns again, and the street dangers brought by the explosion in drug traffic. But the police are also often lazy and demotivated. A crazily small proportion of them are actually out on the front line. A crazily high proportion go sick and retire early.

Day after day, newspapers reverberate with stories of how the police didn't bother to show; of police lack of interest in following up burglaries; of police failure to apprehend the young lawbreakers under their very noses.

Sure, there are numerous acts of valour and bravery, too, but there are too many incidents where the protection of the public seems to be a low priority.

So Blunkett should be supported, and the Lords should be told that this is yet another piece of prime evidence for terminating the old upper chamber. My only concern is why a government as relatively shrewd as this one has opted to launch a bill in the Lords that stands a good chance of being gutted there and left to die. Is it, perhaps, because Tony Blair isn't quite ready for the confrontation, and wants to soften up public opinion first? Let's hope that, this time, the government has the courage of its convictions.