私し刑けいを加くわえる

expression, ichidan verb

take the law into one's own hands; administer vigilante justice

Used when someone punishes another person without legal authority, often implying a group or mob action.

• 村むら人びとたちは泥どろ棒ぼうに私し刑けいを加くわえた。

  The villagers took the law into their own hands against the thief.

• ネット上じょうで個こ人じん情じょう報ほうを晒さらして私し刑けいを加くわえるのは許ゆるされない。

  It is unacceptable to dox someone and administer vigilante justice online.