The day politicians say they’ll tear up human rights if they get in their way is a day for us all to be afraid. Human rights are not there for the powerful to dispense with when it’s politically convenient. They’re there to protect ordinary people and uphold the basic standards of a civilised society.

Blaming them is lazy and irresponsible – it leads to policies that don’t work, lets cowardly politicians distract from their own failings and poisons our communities with discrimination and division.

After the horrific attack in Manchester, the prime minister stood outside No 10 and said: “Let us remember those who died and let us celebrate those who helped, safe in the knowledge that the terrorists will never win – and our values, our country and our way of life will always prevail.”

On Tuesday she abandoned those values, heralding a raft of unsafe, unfair powers already rejected by previous governments.

Then she said this: “If our human rights laws stop us from doing it, we will change the laws so we can do it.”

What she means is this: If the right to liberty or to a fair trial or not to be tortured gets in the way, she’ll just scrap them – casually disposing with values set down to stop tyranny after the horrors of the second world war.

This is an outright attack on the rule of law – the principle that the arbitrary exercise of power must be controlled by subordinating it to well-defined, established rules. It’s the shield that protects us from would-be tyrants. People are less blasé about those words in countries where the rule of law exists only in their wildest dreams.

So what does May think needs to go to help us fight terrorism? The European Convention on Human Rights – a treatise of fairness, compassion and accountability – is designed to keep us safe and free. It’s the law that helped the Hillsborough families expose the truth and it’s a catalogue of the things terrorists hate, and want to see us lose.

It was the brainchild of Winston Churchill, drafted by British lawyers and one of our proudest achievements

It was the brainchild of Conservative Winston Churchill, drafted by British lawyers and one of our proudest achievements. It remains a beacon for those still fighting for basic rights – which is why apartheid activists united to ask David Cameron not to scrap it.

Human rights laws do not get in the way of tackling terrorism. We can and do deport dangerous people all the time, because national security interests can outweigh their rights, and the police and intelligence agencies have a panoply of powers to watch, search, detain and imprison terrorists and those that help them.

Some rights we don’t compromise on – the right to life and not to be tortured. But do we want to be part of the club of countries that approve of torture? Is that the vision of the future we’re offering our young people?

All this, and for what? A series of back-of-an-envelope, long-ago discredited policies that will make us no safer. Control orders are unsafe and unfair, leaving potentially dangerous people who should be dealt with by our courts in their living rooms. Which is presumably why May voted against them in 2005. David Davis rigorously opposed them too. Doubtless he – like many other principled Conservatives – has serious problems with these reckless plans.

Instead, May should lift the ban on using intercept evidence in court, which would put more dangerous criminals behind bars.

She’s also calling to extend pre-charge detention (we’ve seen this somewhere before too). Extending to 28 days would put us way out of step with comparable democracies – it’s 48 hours in the US – and in line with oppressive regimes. It’s totally unnecessary: of 55 people arrested in 2015 on suspicion of being a terrorist, 93% were held for less than a week and there’s no suggestion it would have made any difference in recent months. The Conservatives themselves campaigned against lengthy pre-charge detention in opposition.

Our police and security services already have robust, wide-ranging powers. It’s a crime to incite violence. People suspected of terrorist activity can be stopped and searched. People who aid terrorists are imprisoned and those convicted of plotting an attack can be locked up for life.

Instead of putting the whole population under blanket surveillance, agencies could focus on robust targeted surveillance of suspects, like interception and hacking.

And if the government is serious about protecting people from this violent ideology, they should launch a full independent review of the failing Prevent strategy, look at the evidence and give us a programme that’s fit for purpose.

So why did May make that speech? Authorities come under pressure to explain why they didn’t stop attacks despite these criminals having being brought to their attention. The prime minister is criticised for her Home Office record. The oldest confidence trick in the book – don’t look over here, look over there!

Promising to defend our values and then actually doing so is harder than resorting to kneejerk populism.

Liberty is cross-party, non-party. We and our members campaigned as forcefully against Tony Blair’s plans to extend detention without charge as we have against this government’s ideological obsession with ending universal human rights.

And there’s hope. There’s been no public debate on these plans. They’re not in the manifesto. Even if Theresa May wins, she cannot claim a mandate on this. And many senior Conservative MPs will fight against it.

General elections have a way of making us look ourselves in the mirror and ask what kind of country we want to be. Last night shows that – whoever wins – we need to ask how we’ve come to a place where compassion, decency and fairness have become dirty words in politics.

Our politicians work for us. We need to stand together in telling them that our freedom isn’t theirs to give away.

• The subheading of this article was changed on 8 June 2017. An earlier version referred to the European charter. That should be European convention.

