Donald Macintyre: Despite blundering into Brass Eye, Mr Blunkett has made a good start

August is a wicked month for home secretaries. Who can forget Kenneth Baker rushing back from holiday to fight for his job after the escape from Brixton prison of two IRA terrorists? It was a reminder that not many politicians enhance their reputation at the Home Office. The best that most can hope for is not to lose it altogether. The figures on the number of asylum-seekers in prison are a reminder of the manifold problems that lie in wait for the holders of this great, but ever-turbulent, office of state.

The question is whether David Blunkett can prove an exception to that rule. He has had an interesting first six weeks. He would have done better last weekend to hold his fire on Channel 4's controversial Brass Eye. But he has pleasantly surprised those who feared that he would make liberals nostalgic for Jack Straw. Within days of taking office, he had sensible things to say about the need for a more flexible green card– type regime for immigrants needed to fill jobs that others won't, or can't, do. He struck an impressively civilised note in his condemnation of the hysteria which attended the release of Jamie Bulger's killers. He made clear that he was not trying to shut down the growing debate on the future of soft-drugs legislation. And his sacking of Paul Whitehouse, chief constable of Sussex Police, for promoting two officers who had been investigated for their part in a shooting, sent out a powerful signal that he was not going to be pushed around by policemen, however senior. Which suggests that while he is straining to achieve reform in police efficiency through consensus by inviting police organisations to come forward with their own ideas, he will not merely take the line of least resistance when it comes to making decisions about modernising one of the last unreconstructed nationalised industries.

The picture of Blunkett as a crude authoritarian was always simplistic. More perhaps than any other front-rank politician – apart from Gordon Brown who invented the mantra for Tony Blair – he appears to understand the need to be tough on the causes of crime, as well as on crime itself. On the other hand, there is something to his authoritarian image. He is no "Hampstead liberal" to use one of his predecessor's favourite phrases. Sentimental about banging up persistent villains he isn't. But in any case his approach so far points to something more important. And this concerns the balance that a home secretary in a second Labour term should be striking between civil liberties and the fight against crime.

The formidable agenda Blunkett has inherited includes some radioactive elements. Some of the proposals expected from Lord Justice Auld's delayed report on reform of the courts will make the Mode of Trial Bill – which removed the automatic right of trial by jury for offences ranging from grievous bodily harm to theft, and was blocked in the last Parliament by the Lords – seem like a picnic.

There will also be proposals to give juries, before they reach their verdict, detailed information about the defendant's criminal record – even though that could say more about the reasons the defendant was charged than about his guilt. And the manifesto commits the Government to abolishing the double-jeopardy rule in cases of murder, even though it is difficult to see how second juries would not be prejudiced by the fact that the Court of Appeal had sent the cases for a re-trial. The campaign against such proposals, if they are legislated upon, will not be confined to liberally inclined lawyers such as Helena Kennedy, redoubtable a champion as she will be. For they strike at ancient rights, deeply embedded in the country's unwritten constitution.

Equally, however, there is another constituency, also present on the left, which takes a much more Draconian view. Since the election, I have been struck by how many Labour MPs, particularly new ones from urban seats, are preoccupied with crime almost to the exclusion of other issues. Seats on Chris Mullin's home affairs select committee were coveted, maiden speeches on law and order crafted. This faithfully reflected the stridently expressed concerns on the doorstep, especially in poorer areas, during the election campaign. On some of the estates which most testify to the social dislocation of a brutally reconstructed economy during the Thatcher years, crime, vandalism and street disorder are a blight above all others. Many Labour MPs who live in such constituencies, Mr Mullin included, have little hesitation in seeing the incarceration of the worst offenders as a necessary, if insufficient, condition of restoring hope, pride and civic engagement on such estates.

But Mr Blunkett shows signs of understanding the dangers of widening the gulf between these constituencies. Indeed, he has referred to it, telling the Probation Service earlier this month: "We cannot have what is often called disparagingly the chattering classes on the one hand, and the people I represent whose lives are made a total misery on the other. If we do, my voters will disengage. People who have reasonably comfortable homes and prospects don't disengage. They're the ones who voted substantially on 7 June. It's the disaffected, the alienated who don't. So let's not pose these things any longer in terms of justice and liberty on the one hand, and those of us desperate to protect our communities on the other. The two must come together."

Mr Blunkett saidhe would rather prevent people from going to prison than putting them there for the sake of it. He is unlikely to be any less squeamish than Mr Straw about taking a Draconian approach, especially to violence and sexual offences. But he has floated the idea of "custody minus" in which offenders would be given basic education and life skills and only imprisoned if they re-offended. He has retained the strong interest in prison education – and rehabilitation – that he had in his last post.

There is a crucial point if Mr Blunkett wants to make a fresh start in the second term, as he seems to do. Labour no longer needs to persuade Middle England that it can be as tough on crime as the Conservatives claimed to be. Nor does it have to put forward proposals that are more Draconian than effective simply to make the right headlines in the right tabloids. This is a liberation. It means that it can now afford to cherry-pick the most effective expert proposals laid before it on an admittedly outdated criminal justice system without looking over its shoulder at the focus groups. If Mr Blunkett fails to strike the balance that he appears to promise, he threatens to fracture the coalition of social reformers and libertarians of which his party is historically composed. If he succeeds, he might just be that exception, a great Home Secretary.