Judge Robert Jay gave the decision on Wednesday following a five-day hearing in November. The ruling does not determine if Begum can return to the UK, but whether the removal of her citizenship was lawful, reports CNN.

Shamima Begum was one of three schoolgirls who left the UK capital in 2015 to join ISIL terrorist fighters in Syria.

Aged 15, she married an alleged ISIL combatant and gave birth to two children while still a minor, and then a third after turning 18.

All three children died, the third while they were detained at Al Hol refugee camp in northern Syria.

In 2019, then-Home Secretary Sajid Javid removed her British citizenship.