I occasionally ask the asylum seekers at my constituency surgeries why they made the very long journey to the United Kingdom rather than a much shorter one somewhere else. The answer is almost always the same: it is better here. People have more rights and greater protection.

Similarly some of my Muslim constituents will say that whatever criticisms they have of Britain, they cannot think of a better country in Europe, or for that matter the Middle East or South Asia, in which to live freely and to practise their faith in an atmosphere of tolerance and respect. More generally, despite the claims of a systematic erosion of liberty by those organising this weekend's Convention on Modern Liberty, my very good constituency office files show no recent correspondence relating to fears about the creation in Britain of a "police state" or a "surveillance society".

I'm the first to accept that Labour since 1997 has not achieved a state of grace in terms of the crucial balance between security and liberty. But on any objective basis, this government has done more to reinforce and strengthen liberty than any since the war.

Part of the problem for those who question this is that their analysis assumes the loss of a golden age of liberty. No such age existed. The 60s, 70s and 80s were the decades of the informal "judges' rules", the absence of statutory protections for suspects, "fitting up", egregious abuses of power, miscarriages of justice, arbitrary actions by police, security and intelligence agencies, phone tapping without any basis in statute law or any legal protection for the citizen whatsoever, gaping holes where there should have been parliamentary scrutiny.

As the director of Liberty wrote in 1989: "The last 10 years of government have had a striking effect upon freedom in the UK. Civil liberties have not just been eroded, they have been deliberately attacked and undermined." Almost 10 years later there was still no overriding and systematic protection for people's rights and liberties. Labour has provided that: it's called the Human Rights Act. So long as we are in power it won't be watered down.

The fundamental universal rights enshrined in the act are not contingent on behaviour, but nor do they come without responsibility. Implicit in the act is the notion that we all owe one another obligations in the way we exercise our rights. The forthcoming green paper on a bill of rights and responsibilities is designed to generate public debate about how we can articulate these implicit duties more explicitly.

Even the convention rights enshrined in the HRA are not absolute. The right to liberty itself can be taken away in a variety of circumstances - not least if you are convicted of a serious crime. This gets to the heart of the debate about modern liberty. Can individual rights ever be restricted in the name of the common good? I believe there are times when it is necessary to impose restrictions on some aspects of individual liberty in the interests of wider security. That is one of the central tasks of government. Indeed, as James Madison said, if people were angels, there would be no need for government. But sadly people are not all angels.

The climate in a post-9/11 world is much harder than anyone imagined, even in the immediate aftermath of that outrage. I do not pretend we've got everything right. We haven't. Take the data-sharing measures proposed in the coroner's and justice bill. Their aim is good, but parliamentary scrutiny has thrown up justifiable concerns that the powers provided could be misused. It's not our intention but I agree, so we are acting to get a much better balance between data protection and access to services.

And while the ends can never justify the means, our motives for seeking better protection for citizens from terrorism and crime are hardly ignoble. Those who cast myself and my colleagues as Orwellian drones engaged in some awful conspiracy planned in Whitehall basements not only overlook all this government's achievements, they cheapen the important debate about getting the balance right so that a very important freedom, that to live without fear in an atmosphere of tolerance and respect, is nurtured and protected.

And there is of course an ultimate check on executive power - democracy. Talk of Britain sliding into a police state is daft scaremongering, but even were it true there is a mechanism to prevent it - democratic elections. People have the power to vote out administrations which they believe are heavyhanded.

When people come to assess the choices available at the next election, I will stand proudly on Labour's record, from the Lawrence inquiry, which reported 10 years ago this week, progressive legislation on race and gender, to devolution, the Human Rights Act, Freedom of Information and much more, and be ready to be judged on it. I hope that in the final reckoning even some of our harshest critics will concede that this Labour government has done more than any before it to extend liberties and to constrain government.

• Jack Straw is the justice secretary

strawj@parliament.uk