The paper is focused on the application of intelligence operations in countering transnational organised crime (TOC) and reviews the accompanying legal aspects and effects. The purpose of this qualitative paper is to assess the topic from a global viewpoint and establish methodology for examining, evaluating and addressing the execution of intelligence operations; as performed by the global, regional, national, law enforcement or military intelligence entities. The collection of intelligence and the use of liaison may have political or foreign affairs consequences hence the importance of considering the existing and applicable legal frameworks or constraints. Some operational approaches cause policy and human rights concerns; however these may be the result of the lack of international or internal cooperation and/or available legal instruments providing for alternatives. The topic is not a time-stamped snapshot but is instead a subject to constant changes in terms of shifting environments and contributing viewpoints for assessing its status; therefore in need of continual updating.