Her British citizenship was revoked on national security grounds shortly after she was found, nine months pregnant, in a Syrian refugee camp in February 2019.
Ms Begum, now 23, is challenging the Home Office’s decision to remove her British citizenship, with her lawyers arguing that the department had a legal duty to investigate whether she was a victim of trafficking when the decision was made.
On Tuesday, Samantha Knights KC, for Ms Begum said: “In this case we say there were missed opportunities, both at the school… and in relation to the police and the secretary of state taking the decision to deprive, must take those failings into account.”
Ms Begum’s lawyers have said that she was “recruited, transported, transferred, harboured and received in Syria for the purposes of ‘sexual exploitation’ and ‘marriage’ to an adult male”.
In written submissions, Ms Knights and Dan Squires KC said there “were a series of obvious questions of individual, local and national importance as to whether steps could and should have been taken” by organisations including the Metropolitan Police, Ms Begum’s school, the Home Office and the security services “that might have prevented the girls’ travel or led to their interception before they arrived in Syria”.
The barristers said there were questions about whether “key indicators” that Ms Begum and her two friends were at risk of being trafficked were missed by the police or security services.
Ms Knights told the court that while a victim of trafficking could still be prosecuted or deprived of their citizenship, “terrorism and trafficking are inextricably linked”.
The Special Immigration Appeals Commission (SIAC )previously heard that part of the test before a person is deprived of their British citizenship is whether it is “conducive to the public good”.
She later said that any potential failure by state bodies “needs to be investigated because it goes to the position of conducive to the public good.”
In written submissions, Sir James Eadie KC, for the Home Office, said there was “no ‘credible suspicion’ that she was a victim of trafficking or was at real and immediate risk of being trafficked prior to her travel from the UK”.
He continued: “At 10 December 2014 both the police and Ms Begum’s school turned their minds to the question of her potentially travelling to Syria to align with ISIL. However, both considered the risk was low.”
Sir James said that Ms Begum’s case requires her to prove that her school, local authority and the police “fell into error in their assessment of the same issue at the same time”.
“The deprivation decision cannot be retrospectively invalidated by alleged failings to properly investigate, which are said to have occurred after Ms Begum left the UK, and by other entities which were not involved in the deprivation decision,” he continued.
The barrister said that Ms Begum would have to prove that “multiple investigations” were inadequate, adding: “There is no evidential foundation for that.”
“What Ms Begum cannot do is speculate to generate a hypothetical link between what further investigation by those entities might have achieved, and the investigation that was undertaken here,” Sir James added.
He later said it was “entirely possible that someone may have been trafficked – which the secretary of state does not accept occurred in this case – but remains a risk to national security”.
Sir James said that the then-home secretary took into account Ms Begum’s age, how she travelled to Syria – including likely online radicalisation – and her activity in Syria, when making the decision to remove her British citizenship.
The hearing in London before Mr Justice Jay is due to finish on Friday, with a decision expected in writing at a later date.