Definicija: izvajajo tako, da prizadeta oseba zanje ne ve, hkrati pa predstavljajo posebej težke posege v temeljne človekove pravice, npr. v pravico do zasebnosti

Definicija: surveillance is covertif, and only if, it is carried out in a manner calculated to ensure that any persons who are subject to the surveillance are unaware that it is or may be taking place; it includes monitoring, observing or listening to persons, their movements, conversations or other activities and communications