On December 25, 1887, hoan jorei (regulations for the preservation of law and order), which aimed to remove 'security risk' from neighboring area of Imperial Palace was issued as an imperial edict, as Jiyu Minken Undo (Movement for Liberty and People's Right), including Daido Danketsu Movement and Sandai Jiken Kenpaku Movement, heated up.
1887年（明治20年）12月25日、三大事件建白運動や大同団結運動など自由民権運動の高揚に対し、皇居付近から「危険人物」を排除する事を目的とした保安条例が勅令によって公布された。