The MJIB is responsible for both political intelligence gathering and criminal investigations, and is nominally under the Ministry of Justice. Its work overlaps with that of the NSB, and the existence of two different chains of command inevitably creates problems.
調查局業務兼容政治偵防及犯罪偵查兩大項，名義上隸屬法務部，但工作範圍又與國安局重疊，難免有指揮二元體系的弊害。