The duty of police is to root out violence and bring peace to the good.
Tips
history
Recorded in Song-dynasty 《太平广记》 (Tàipíng Guǎngjì) by 李昿 — '舍之职责,在乎除暴安良' ('a duty consists in rooting out violence and pacifying the good'). It became the stock motto of 武侠 (wǔxiá) heroes in fiction.
usage
Mirror structure: 除暴 'remove violence' + 安良 'pacify the good'. Modern use covers police work, vigilante heroes, and even corporate 'cleaning house' — but always with a moral, not bureaucratic, tone.