Two weeks ago, the world was left reeling in the wake of two days of brutal violence in Paris.

Initially, political leaders in Britain responded with fervent promises to preserve free speech and democracy in the face of arbitrary violence and tyranny. Shortly after the Charlie Hebdo attack, David Cameron told MPs: "These people will never be able to take us off those values."

Sadly, the days since have seen a predictable chorus of voices calling for more powers for our spies – MI5 head Andrew Parker, Intelligence and Security Committee chair Malcolm Rifkind and now the prime minister himself. In these pre-election days, the "Snoopers’ Charter" seems firmly back on the agenda.

In the wake of such a barbaric attack, it’s easy to belittle or dismiss concerns about state snooping on innocent members of the public - "this civil liberties stuff," as Mayor of London Boris Johnson put it.

But, looking past hysterical headlines, hyperbole and rhetoric, will giving our spies more powers make us any safer? And does anything about the Paris attacks suggest an urgent need for yet more sweeping surveillance?

Nothing about the Paris attacks points to a need for more blanket surveillance powers: Like the murderers of Fusilier Lee Rigby, the Paris attackers had been known to authorities for years. Gathering intelligence on the entire French population would have made no difference.

The UK security services already have extensive powers: Since 2009, the government has placed obligations on UK service providers to retain communications data – who we phone, text and email and much more – for 12 months through a blanket regime. Last year, the DRIP Act reaffirmed this power – and claimed astonishing new ones that attempt to require interception by companies outside the UK. Meanwhile, post-Snowden, the agencies continue to collect and intercept millions of emails, messages and web chats entering and leaving the country every day. The Counter-Terrorism and Security Bill extends surveillance powers further, including a new power to intercept our post without warrant.

But mass surveillance doesn’t work: We saw similar cynical calls for a resurrection of the Snoopers’ Charter following the murder of Lee Rigby in 2013. But, it would not have prevented his death. In fact, the cross-party committee that looked into the handling of his killers and reported in November exposed major internal failings in the way the agencies pursue leads and prioritize suspects. It found that both men had been known to the agencies for years, one had even been considered a priority suspect – but basic problems, such as delays, poor communication and bad record-keeping, prevented targeted intrusive surveillance of the suspects being carried out in time. The Snoopers’ Charter would, perversely, build an even bigger haystack of data for agencies to trawl through – and make prioritizing suspects even more difficult.

Targeted, proportionate surveillance: Surveillance per se is not wrong. It’s the vital task of the government and security agencies to protect life through targeted and effective monitoring. But the Snoopers’ Charter would be neither targeted nor effective. Instead of political posturing over new powers that would undermine all our freedoms, we need the agencies to focus on improving their internal systems for prioritization. Invading the privacy of suspected terrorists is justified. Invading the privacy of every single person in the UK is not.

The Snoopers’ Charter would sacrifice our privacy and our free expression – without making us any safer: It would turn us all into suspects, wasting huge resources monitoring the activity of everyone man, woman and child in the country. It would make us all less free, but no safer – not much of a trade-off.

In confronting an ugly ideology that promotes violence, the subjugation of women and tyranny, we would expect our political leaders to actively promote democratic values like human rights. Instead, by resorting to knee-jerk, headline-grabbing proposals, the Prime Minister is playing straight into the hands of terrorists – allowing them to shape our laws and erode those very principles.