This chapter focuses on directed surveillance, which can be conducted if and only if necessary for the purpose of preventing or detecting crime or of preventing disorder. It introduces the two-part hierarchy of surveillance prescribed by law: directed and intrusive. It also describes empowered public authorities that utilize intrusive surveillance, which are defined by reference to senior authorizing officers within each organization that can grant an intrusive surveillance authority. The chapter outlines organizations that may conduct intrusive surveillance and those empowered to conduct directed surveillance. It cites the Regulation of Investigatory Powers Order 2010 that requires surveillance to be regarded, treated, and accordingly authorized as intrusive surveillance.