The Home Office has argued that it was justified in revoking Shamima Begum’s citizenship even though she was trafficked to Syria and “brainwashed”.
Sir James Eadie KC said the threat to national security was the most important factor in making the decisions, not how a person came to pose that danger.
He told the Special Immigration Appeals Tribunal (SIAC): “You can be treated in the most appalling, unacceptable way, exposed in the most unacceptable way, desensitized in the most unacceptable way and yet, unfortunately… still be a security threat.
“If they pose such a danger, it doesn’t matter how they came to pose that danger. What matters is that they actually pose such a danger.
“No one disputes that it is entirely possible for a person to have been trafficked or manipulated or brainwashed or the like and still be the most serious danger to the public”.
Mrs. Begum was 15 years old when she traveled from London, through Turkey, into territory controlled by the so-called Islamic State.
Now 23, she is challenging the decision to strip her of her citizenship on national security grounds after she was found nine months pregnant in a Syrian refugee camp in February 2019.
SIAC heard that, according to the security services, people who traveled to Syria to align themselves with IS were “likely to have been radicalised, to have contributed to the continuation of Isil as an entity and may have received military training, fought with Isil or participated in terrorist attacks “.
Begum’s lawyers said she was “recruited, transported, transferred, housed and received in Syria for the purposes of sexual exploitation and marriage to an adult man”.
Sir James has previously said that then Home Secretary Sajid Javid was aware of Ms Begum’s “age and the circumstances of her travel to Syria” when he made the decision to strip her of her British citizenship.
He said Ms Begum traveled to Syria “with her eyes open” to the brutality of IS.
“She traveled with the intention of aligning herself with Isil and once in Syria she joined Isil.
“The assessment is that she did it with her eyes open. Isil’s ideology and their uncompromising brutality had been widely covered in the media,” he said.
Begum’s lawyers claimed she was “persuaded” by friends and an “effective Isis propaganda machine”.
The court heard this on Wednesday Mrs Begum’s mother’s world “fell apart” after her daughter ran away from home.
The hearing in London, before Mr Justice Jay, is due to conclude on Friday, with a decision expected in writing at a later date.