It was actually the
Counter-Terrorism and Border Security Act 2019 I was thinking of. I think the problem with the legislation you’ve highlighted is proving membership of a group, especially when that happened in Syria. She may have had online exchanges with people in this country but her legal team would argue that didn’t constitute membership of ISIS. Obvs, the 2019 Act couldn’t be retrospectively applied to Begum.
The below is from the HoC library:
In addition to using TEOs, the Government has said repeatedly that it would
seek to prosecute anyone who has travelled abroad to engage in terrorism related activity. There are a number of terrorist offences that might be relevant, including belonging to a proscribed organisation, or attendance at a place used for terrorism training. However, there may be difficulties in obtaining evidence of conduct that has taken place abroad, in territory without a functioning criminal justice system that UK authorities could cooperate with.
The
Counter-Terrorism and Border Security Act 2019 introduced a new offence of “entering or remaining in a designated area” aimed at addressing this difficulty. The new offence would apply to those simply travelling to certain designated parts of the world, without the need to provide evidence of terrorism-related activity whilst there.