It’s obvious why the rise in violent crime – and knife crime in particular – grabs people’s attention. It’s horrific, it disproportionately affects the young, and it’s downright scary. The idea that someone you pass in the street might mutilate or kill you or those you love for the tiniest offence, or for no reason at all, tends to stick in one’s mind.

That applies from a distance, if you hear about it on the news or read about it in the paper, but as a father of young children living in South London I can confirm it applies all the more when you’re physically rather more near to the events in question. And it seems that the proportion of the country who find themselves in relatively close proximity to such crime is rising. While the London murder rate, and the seeming absence of the capital’s mayor, is often the go-to reference, police statistics suggest a rise in violent crime involving a knife in every region of England and Wales. There is local variation, including a few forces which have seen a fall to some degree, but overall the police recorded 28 per cent more violent crimes including a knife in June 2017-July 2018, than in April 2010-March 2011.

It’s a particularly stark change because we have more generally enjoyed a sustained fall in most types of crime for several years now – part, as per Steven Pinker’s book The Better Angels of Our Nature, of a trend seen in many similarly developed countries. The fact might be that you’re less likely to be a victim of crime than ten or 20 years ago, but the good news of hypothetical crimes failing to occur does not outweigh the grim sight of kids bleeding on the pavement, for obvious reasons.

Rightly in a democratic society such horrors leap from the streets into the minds of the public and the pages of the press and thereby onto agendas in Westminster. It’s a measure of concern about the issue that while other topics are swamped by the dominance of Brexit, knife crime in particular has established itself as a major question of the day. As City Hall and Whitehall are yet to produce a clear answer, the clamour for action will surely grow – as will the tally of attacks.

The poser for policymakers is what to do that will actually work. Inside and outside the police, stop and search has become a common answer. The implication is that Theresa May’s decision as Home Secretary to limit the use of the power is responsible for the rise in stabbings, and that reversing those changes would duly nip the problem in the bud.

There are a few problems with this theory. For a start, let’s remember what May’s policy and reasoning (cited by this site in 2015 as a Reason To Vote Tory) actually were. Home Office statistics (albeit now disputed by one source) suggested the power was used disproportionately against ethnic minority people, without any sign of a resultant higher rate of arrests, which troubled her on two levels – first as an unjust mistreatment of innocent people by law enforcement, and second as a waste of police time and resources. She took the view not that stop and search was wrong, but that misusing it was an ineffective way to fight crime.

As Stephen Bush summarises in the New Statesman, by cutting the number of suspicion-free stops, and raising the proportion of stops which led to an arrest, May’s reforms essentially kept the number of actual criminals being stopped and caught the same, while reducing time wasted and resentment incurred among the innocent. As Bush points out, David Blunkett’s 2001 experiment, in simply reducing the number of stops generally, produced an almost immediate rise in crime, while May’s specifically targeted reduction in 2014 did not.

It might be, of course, that while May’s approach did not cause crime directly it might instead have made policing vulnerable to a problem which has subsequently arisen. We know that organised criminals are adept at identifying and taking advantage of flaws in police procedure – the widely-reported practice of scooter gangs taking off their crash helmets in the knowledge that doing so meant pursuing police officers were forbidden from knocking them off their bikes is a good example.

Perhaps what we’re seeing now is a change in criminal tactics to belatedly take advantage of the stop and search reform. Maybe it’s something else – changes in the subculture of crime, or Trevor Phillips’ idea that it represents the influence of refugees from war zones, or a shift in the economics of the drug trade, or a symptom of the expansionist strategy of ‘county lines’ gangs, or all of the above.

It falls to the Home Secretary to take a clear, swift and effective decision about what to do in response.

The police want a drastic relaxation of the requirement for suspicion, and they have a following wind in the press. Politically, it would be easiest just to give them exactly what they want, and boast of one’s toughness.

Doing so might tick the “clear” and “swift” boxes, but it’s not certain that it would also be effective. It remains true that targeting suspects has a higher hit-rate than targeting people without suspicion, and even if there were sufficient resources to sizeably expand police numbers (which there aren’t) it wouldn’t be wise to squander officers’ time on inefficient tactics. Furthermore, not all police officers used such powers fairly or even legally in the past – simply undoing May’s reforms would risk undoing any gains in trust made among those who were unfairly stopped without good reason under the old system.

The Government definitely wants to lower the barriers faced by police in the fight against knife crime, and be seen to do so. But it cannot simply repeat policies that don’t work properly.

Notably, Javid’s recent discussion of cutting bureaucracy around stops and making police confident to use the power was still couched in terms of requiring grounds for suspicion: “If the police think that there’s good reason that they may be carrying an offensive weapon, the police should be absolutely empowered to stop them.” His eventual answer, when it comes, has to persuade people that the law can be enforced while maintaining that principle. And then, crucially, it must work.