For the moment, she is beyond British law, holed up in a refugee camp in Syria. Only a new law can bring her to justice. And there is good reason for that to be a modern law against treason – the very offence she committed by renouncing her allegiance to Britain and joining a terrorist group in Syria.

Critics may dismiss this as an unreasonable law – a medieval one. But it is entirely justified. Britain is in an unhappy spot. Many hundreds of our young people travelled abroad to join and to fight for Isis (aka Islamic State) during its most territorially expansive days. Although thankfully many of those terrorists were killed on the battlefield by the international coalition and its allies, many more remain. Some of them are in prison camps like Al-Hol in Syria – a place where Isis is plainly in force and in strength. Others are the prisoners of regional partners like the Syrian Kurdish YPG – whose loyalties are ever-shifting and who have repeatedly warned of the inevitability of prison breaks and escapes.

Prosecuting foreign crimes committed in war is difficult. Documentary evidence is lacking. Witnesses cannot be located. Often no one wants to talk. We know that joining Isis is akin to joining both a murderous cult and a criminal gang. Members condoned and committed much evil violence. But we cannot prove that sufficiently to charge them under current laws.

All the while, in the press and on TV, we are treated to the farce of people like Shamima Begum attempting to defend themselves before the public gallery. Begum is someone who should be in court, not on television. But without a new law – a new Treason Act – the state is uncertain how it could begin to try someone in her position.

A Home Office effort to update Britain’s treason laws in order to better prosecute terrorists has been recently held back by Dominic Raab. Raab has apparently done this because, as Lord Chancellor, he is worried it is “bad law”. This is a valid thing for him to be concerned about. But compared to the challenges of terrorism, this is rather comparing a molehill to a mountain.

This is something the Home Office proposal is intended to solve. It aims to use treason charges to prosecute hackers, terrorists, and those who swear allegiance to a foreign power. This is all entirely reasonable; and if the laws do not exist to prosecute these people already – something we can already see in evidence – they must be created urgently. It is a good proposal, and I hope it is – as fast as possible – brought into being.

People complain that treason charges have two negative effects. In one case, some are squeamish about labelling wrongdoers as ‘traitors’. They worry about the possible stigma. Others – like Baroness Williams of Trafford – think, entirely the opposite, that to do so might in some way glamorise terrorism. These perspectives are mutually exclusive, of course. They are also wrong.

Shamima Begum wants to return to the UK (Picture: BBC)

First, jihadism is explicitly anti-state and anti-nation. The people who believe in it believe that there are only two types of people: believers, who should be spared, and infidels, who should be exterminated. There is not place in any of that for national identity and political allegiance. To swear adherence to a terrorist leader like Abu Bakr al Baghdadi, the former leader of Isis, or Osama Bin Laden, the former leader of al-Qaeda, is by definition to renounce nation and state. It is treason, pure and simple.

To use fashionable language of alienation: these people are not ‘othered’ by dint of labelling them traitors; they have already decided they are an ‘other’ and apart from everyone who does not share their violent, delusional ideas. The same is true of anyone who fights, or hacks on behalf of the North Korean, Iranian or Russian states. By swearing allegiance to a foreign enemy, they have clearly renounced their ties to the British state. The law must take account of this and have the tools to punish them.

As for glamorising those who commit violence, unsurprisingly, Baroness Williams is wrong and entirely out of touch. The jihadists already glamorise themselves quite effectively. Most of the narrative when Isis appeared was about its slick presentation. Its videos were edited brilliantly. Its narrative of caliphate was attractively presented. It appealed to fantasies of a new life, and a life of respect and ‘glorious’ violence.

What has undermined this glamour was – first – military defeat. It is hard to look glamorous as a prisoner, or a corpse. And second, prosecution. Isis members are hardly Nelson Mandela. They will not look appealing or morally good in the dock. A treason law is therefore not only a theoretically appropriate tool for responding to these threats, it is eminently practical too.

A CCTV image of (left to right) Kadiza Sultana,16, Shamima Begum,15 and Amira Abase, 15, going through security at Gatwick airport as they travelled to Syria in 2015 (Picture: Metropolitan Police/PA Wire)

At the moment, the law in the UK is suffering and struggling. It cannot find a way to repatriate Isis brides and fighters and guarantee the convictions they richly deserve. But there is a path to end this stalemate and to give Isis’s victims justice. That path is the creation of new treason legislation. It is the right and necessary thing to do.

Dr Azeem Ibrahim is a director at the New Lines Institute for Strategy and Policy in Washington DC, a former member of the UK Commission for Counter-Extremism and author of Radical Origins: Why We Are Losing the Battle Against Islamic Extremism.

Isis member Shamima Begum's case shows why a new treason law is needed to tackle terrorism – Dr Azeem Ibrahim