専せん決けつ

noun, noun or participle which takes 'suru', transitive verb

decide or act on one's own authority; arbitrary decision

Often used in formal or organizational contexts where someone makes a decision without consulting others, sometimes with a negative nuance of overstepping authority.

• 部ぶ長ちょうは部ぶ下かに相そう談だんせずに専せん決けつで契けい約やくを結むすんだ。

  The department head signed the contract on his own authority without consulting his subordinates.