One set is a list of international pre-charge detention limits and the other is the proposed trajectory of pre-charge detention in the UK.

Despite a consensus that spans the worlds of political parties, law, policing, religion, media and public opinion, the Government is blindly pushing ahead with controversial plans to extend detention without charge from 28 to 42 days.

This desperately counter-productive measure is unjust, unnecessary and will not – as the Government has argued – make us any safer.

In the past week we have had a veritable feast of so-called concessions wafted in front of us; clearer definition of a terrorist threat, strengthening the role of Parliament, the temporary nature of the power. Before we allow ourselves to be seduced by purple prose, we should have a much closer look at what is behind this soothing rhetoric we are being fed.

Vitally, these are still not emergency powers – the proposals may be dressed up in the language of "grave and exceptional terrorist threats", but there is still no legal requirement for a terrorist emergency to exist and no requirement for the Home Secretary to show that 42 days detention is urgently needed to deal with any threat.

The nightmare scenario, often drawn upon to justify this extension, of police overwhelmed by multiple terror plots, is not what this legislation is restricted to addressing. As the Bill stands, despite the amendments, 42 days detention without charge could still become routine, triggered for operational convenience in individual cases.

The Parliamentary oversight trumpeted is no improvement either. No matter how diligent our Parliamentarians, this would still be nothing more than a rubber-stamping exercise. As the powers would still be triggered to deal with named individuals in custody, this would still involve Parliament debating individual cases. This could prejudice future prosecutions and compromise cases. Surely our Parliamentarians deserve more respect than this?

The judicial oversight is just as worthless. The role of a judge in approving the use of pre-charge detention is of little comfort; before a person is charged there is, by definition, no evidence for a court to test. The judge would have nothing more than police suspicion to base their decision on – the judge as the referee of a match, but with only one team on the pitch. This is why the courts have not once rejected an application to hold suspects for between 14 and 28 days. Neither could the courts overturn these "reserve powers" if, like Liberty, they consider them in breach of our basic rights and freedoms.

These fig leaf amendments, then, turn to ash when given more than a cursory glance – only those who are happy to be hoodwinked will accept this attempt to repaint this ill-conceived piece of legislation. For the rest of us, we see it for the mirage that it is.

Of course the threat of terrorism is very real and very grave – but the fight against terrorism has not come to a dead end, with extension to pre-charge detention the only writing on the wall. There are alternatives, long suggested by Liberty, that the Government could implement instead. The use of intercept evidence in the courts and post-charge questioning, for example. Surely we have the same wit and wisdom as the many democracies around the world that use the products of interception as criminal evidence? Post-charge questioning, providing the person has been properly detained and charged in the first place, and with effective judicial oversight, can give the police time to charge but continue to investigate a suspect's involvement in something more serious.

There are also existing laws and practices that undermine the argument for extending pre-charge detention. The Director of Public Prosecutions has said that longer pre-charge detention is unnecessary because charging practice has recently changed to help the prosecution charge terror suspects earlier. Emergency measures in the Civil Contingencies Act could already be triggered in a genuine emergency. With such a wide selection, we cannot say that we are short of options.

So let's return to the fundamentals – this policy is wrong in principle and dangerous in practice. It will lead to injustice and alienation. It will play into the hands of the terrorist recruitment sergeant. It puts us out of step with the international community who are also dealing with the threat of terrorism. It makes a mockery of our proud history of British justice and fairness.

So back to our bingo cards. Eyes down. Canada, one day of pre-charge detention; US, two days: Russia, five days; France, six; Ireland, seven. United Kingdom… what is it to be? The status quo and our conscience and reputation intact – or extension and a poisonous legacy that will outlive us all?

Shami Chakrabarti is the director of Liberty.