On August 9, 2025, the Metropolitan Police in London arrested 474 protesters during a large demonstration in support of the banned group Palestine Action in Parliament Square. The protest was organized by Defend Our Juries and saw hundreds of participants publicly expressing their opposition to the UK government’s proscription of Palestine Action under the Terrorism Act 2000. Attendees displayed placards and banners with slogans such as "I oppose genocide. I support Palestine Action," highlighting their protest against what they claimed was the UK’s complicity in Israeli actions in Gaza. The police reported that 466 of the arrests were for expressing support for the banned group, with additional arrests made for offenses including assaults on officers and public order violations.

The UK government banned Palestine Action in July 2025 after some members infiltrated RAF Brize Norton and caused damage to military aircraft, claiming responsibility for the act to protest the UK’s backing of Israel's military operations. The ban criminalizes membership or any expression of support for the group, carrying a maximum sentence of 14 years in prison. Despite the ban and police warnings, demonstrators gathered in Parliament Square, chanting slogans such as “hands off Gaza” and holding Palestinian flags. The police implemented a significant presence and repeatedly arrested people showing any support for Palestine Action, including those simply holding signs or wearing supportive clothing.

The Metropolitan Police described the operation as possibly the largest mass arrest in their history, taking protesters into custody at multiple processing points. Those whose identities were confirmed were bailed with conditions preventing further participation in protests supporting the group, while others were held in custody. The crowd primarily consisted of seated, peaceful demonstrators, although police did arrest some individuals for assaults on officers. Nonetheless, authorities reported no serious injuries during the operation. Amnesty International expressed deep concern over the mass arrests, arguing that the protestors were exercising their right to freedom of expression and that treating peaceful demonstrators as terrorists was disproportionate.

The protest underscores ongoing tensions over UK domestic responses to the conflict in Gaza and the restrictive measures imposed on Palestine Action. Critics of the ban argue it undermines free speech and protest rights, while the government maintains that the group poses a threat to national security due to involvement in significant criminal offenses. Legal challenges to the ban have been initiated by the group’s co-founder, Huda Ammori, with courts slated to consider its implications on civil liberties. Meanwhile, the protracted dispute continues to mobilize activists and authorities alike, with further demonstrations and legal actions anticipated in the coming months.