British authorities reported the arrest of 325 individuals on Saturday during a protest in London supporting Palestine Action, a group recently banned under the UK’s anti-terrorism laws. The demonstration took place ahead of a Supreme Court hearing scheduled for Wednesday, which will consider an appeal against the government’s July 2025 decision to proscribe the organization.

The Palestine Action group has been placed on the UK’s list of proscribed organizations alongside entities such as Hamas. Membership in or support for the group is now criminalized, carrying potential prison sentences of up to 14 years. This designation has led to the detention of over 4,000 people to date, including elderly participants and Holocaust survivors, according to figures provided by campaigners and police sources.

London’s Metropolitan Police detailed that of the arrests made during Saturday’s protest, 320 were specifically for expressing support for a proscribed organization under the Terrorism Act. The remaining arrests were for other, unspecified offenses. Demonstrators had gathered primarily outside the US embassy in London to voice their opposition to the ban.

The United States also formally designated Palestine Action as a terrorist organization in August, amid the administration of former President Donald Trump’s broader efforts targeting left-wing groups. This has contributed to the international dimension of the controversy surrounding Palestine Action’s activities and status.

Meanwhile, a smaller group of protesters assembled outside the US consulate in Edinburgh on Saturday. No arrests were made at that location, but Police Scotland announced ongoing investigations into identifying individuals seen displaying items supporting the banned organization. Authorities stated that evidence was under review and that further action would be taken if deemed appropriate.

The forthcoming Supreme Court hearing is expected to address both legal and civil liberty issues related to the UK government’s decision to proscribe Palestine Action, with implications for protest rights and counter-terrorism policy. Supporters of the group argue that the ban infringes on legitimate activism, while the government maintains it is necessary to prevent violence and extremism.