8.31為人大於2014年政改「落閘」5周年，民陣原定舉行集會及由遮打花園遊行至中聯辦，不過被警方以高風險為由發出反對通知書，遊行上訴委員會覆核結果，上訴失敗，維持原判。民陣召集人岑子杰表示上訴失敗會申請在其他日子遊行，強調不會舉辦不合法遊行。抗議警方嚴重剝奪市民和平遊行集會的公民權。
8.31前夕，多名社運搞手被襲，警方就反送中運動進行「大追捕」，繼民族黨召集人陳浩天、香港眾志黃之鋒、周庭、沙田區議員許銳宇及港大學生會前會長孫曉嵐被捕後，3位泛民立法會議員鄭松泰、區諾軒及譚文豪亦先後被捕。區諾軒今早得悉多人被捕後，曾發聲批評「香港已進入全面威權警察國家時代」，濫暴濫捕。
數十萬港人無懼非法集會威脅及間中豪雨，逼爆港島街道，由銅鑼灣至西環，均塞滿黑衣人，向林鄭政府要求回應五大訴求。
August 31 is the 5th anniversary of setting restrictive framework of political reforms by the National People’s Congress in 2014. The Civil Human Rights Front (CHRF) has decided to cancel an anti-extradition law march set for Saturday after their bid to overturn a police ban failed.
Jimmy Sham, convenor of the CHRF, said that they would cancel the rally and march, from Chater Garden to the China Liaison Office, and apply for a march on other days, emphasizing that illegal marches would not be held. He protested against the police’s severe deprivation of citizens’ rights to peaceful demonstration and assembly.
On the eve of 31 August, activists were attacked and the Police conducted a mass arrest on the anti-extradition movement. Following the arrest of National Party Convenor Chan Ho-tin, Joshua Wong and Agnes Chow of Demosisto, Sha Tin District Councillor Hui Yuet-yu and the former Hong Kong University Student Association Chairman Suen Hiu-lan, three pan-Democrat Legislators Cheng Chung Tai and Au Nok-hin, Tam Man-ho were also arrested. Au Nok-hin criticized that “Hong Kong has entered the era of full-authoritarian police state” with police brutality and indiscriminate arrests.
Tens of thousands Hong Kong people took to the streets of Hong Kong Island, undaunted by the threat of illegal assembly and occasional pouring rain. The streets from Causeway Bay to Western District, were flooded with people in black, demanding the Carrie Lam government to respond to the 5 major demands of the protesters.
蔣匡文
張建雄
陳嵐
鄭永年
劉寧榮
盧兆興
褚簡寧
王永平
潘樂德
謝祖墀
劉銳紹
馮珍今