The South African National Defence Force (SANDF) aims to defend and protect the Republic, its territorial integrity, and its people in conformance with the Constitution and domestic and international law principles. Ensuring national security and state functionality requires SANDF members and employees to be security competent, meaning they can prevent unauthorised disclo-sure of classified information. The security vetting process, culminating in a security clearance certificate, assesses this competence. In some cases, polygraph tests are used to verify truthfulness, potentially impacting privacy rights. This paper examines whether such privacy limitations are justifiable within an open society, considering the SANDF’s constitutional mandate to protect national security. Through a military justice perspective, the study evaluates the constitutionality of polygraph testing within the SANDF’s vetting process, emphasising the rule of law and the protection of individual rights and freedoms. The findings assess the governance framework’s validity, aligning it with the Constitution's principles, values, and provisions.