Shamim a.

Begum, was born to Bangladeshi parents and left London in 2015.

When she was 15 years old, she went to Syria via Turkey with two school friends in Syria.

She married an Islamic state fighter and lived in Raqqa, the capital of the self declared caliphate where she remained for four years.

She was discovered in a detention camp.

Begum has had three Children since leaving Britain.

Buttle, the infants have since died.

Britain's interior minister originally stripped her off her British citizenship.

But in July the Court of Appeal unanimously agreed.

Begum, now 21 could only have a fair and effective appeal of that decision if she were permitted to come back to Britain.

Challenging that verdict, James Eadie, the lawyer for the British government, told the Supreme Court that intelligence agency concluded those who were aligned with Islamic state post a serious risk to national security.

Begum's case has been the subject of a heated debate in Britain.

Some argue that she gave up her right to citizenship by traveling to join Isis.

Others argue she should not be left stateless, but rather face trial in Britain.

The Supreme Court hearing is due to last two days, with a decision expected to be handed down at a later date.