This week we were all given reason to question how safe we feel on our streets. On Sunday, a 20-year-old took a knife and injured three people on a busy high street before being shot dead by police officers. Like the terrorist attack on London Bridge, we have once again been confronted with the fragility of life.

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In the aftermath of terror events there is always an immediate call for more to be done to tackle extremism. It is understandable that we want to feel safe, yet at times like this it is more important than ever to remember that public panic is the exact response that terrorism hopes to provoke.

In the race to issue a response, rather than thoughtful reflection on what’s working and what isn’t, it’s tempting for politicians to make bold promises to rid our streets of terror once and for all.

That’s what happened on Sunday after the attack in Streatham. There was remarkably little time for soul-searching. In less than 12 hours, the home secretary was announcing new initiatives to tackle extremism – later revealed to be a promise to lock up terrorists for ever. Sadly for all of us who want a safer world, these proposals did little to offer real reassurance.

Loud, strong-arm announcements that talk of “getting tough” should always be viewed with suspicion. We deserve solutions that work, not kneejerk reactions that entrench the problems they’re supposed to solve. That means we need to be having evidence-based conversations about long-term solutions.

Everyone has a right to serve the prison sentence they were given when they were tried by an independent judge

These should start with an appraisal of the government’s failing Prevent counter-terrorism strategy. It’s a blunt and ineffective tool that can profile children as extremists based on the colour of their skin, and has labelled environment campaign group Extinction Rebellion as a threat. It has become just another instrument of coercion and control that has no hope of addressing the complex causes of violent extremism. It is not based on evidence, its effectiveness has not been reviewed and, given recent events, it’s clearly not working.

Liberty, along with others, has been campaigning to get an independent review of Prevent. This hasn’t happened. A review was announced but had to be deferred after the reviewer was, by his own admission, biased towards Prevent. In the noise of press coverage in the last few days, the government’s silence on this failed strategy is deafening.

Instead, we have a familiar playbook of punitive, short-term measures that may grab headlines but won’t save lives. It’s easy to suggest that locking people up for longer will reduce the threat of terrorism. At best it defers the problem, at worst it leaves people languishing in a broken prison system, stripped of the resources required to rehabilitate them. And if we don’t rehabilitate people, we can never end violent crime.

Over the next week, we’ll no doubt see attention focused on the people convicted of terrorism who are on the brink of release. Those who believe they should be kept locked up while the government sorts out its act should contemplate what they are giving away in the process, and what seeds they’re sowing.

It’s a very old story that if the state abuses the civil liberties of its population it breeds division, mistrust and danger. If this government starts locking people up indefinitely, it will have surrendered the very values that separate us from terrorists. If there’s any doubt about that, reflect on the British government’s policy of internment in Northern Ireland in 1971, and its catastrophic consequences for peace.

While the threat to lengthen people’s jail terms retrospectively might sound like a necessary approach, it also risks breaking the law because everyone – including convicted criminals – has a right to serve the prison sentence they were given when they were tried by an independent judge, not one imposed at the whim of a politician playing to the public gallery.

And to break the law for what? Ultimately, these moves don’t offer solutions. They offer no hope of terrorism being eradicated, no hope of rehabilitation. Not to mention that longer prison terms come with a hefty public spending bill.

What has been lost in all of this is accountability. This should be a chance for the state to reflect on what’s working and what’s not, and to build a strategy that protects all our rights and freedoms and keeps us safe.

We need initiatives that stop us from being victims and discourage us from being perpetrators. As hard as it is to be a voice of restraint at times like these, it’s more important than ever to stick to our principles and stand up to power.

• Martha Spurrier is a British barrister and human rights campaigner and the director of Liberty