The National Security Council Act 2016 (NSCA) came into force on the 1st of August 2016 and is a stringent security legislation that threatens Malaysian democracy because it has provisions that infringes fundamental rights as defined in the Federal Constitution (FC) of Malaysia and the principles of the Rule of Law. Currently, there are a number of laws such as the Security Offences (Special Measures) Act 2012 and the Prevention of Terrorism Act 2015 which were enacted to counter the threat of Malaysians joining the Islamic State of Iraq and Syria (ISIS). Despite the existence of these laws, the NSCA was enacted. Given the laws that already authorize detention without charge or trial, the need for the NSCA has raised questions. This study critically assesses the validity of the attacks that the NSCA contravenes or conflicts with the FC in two stages. First, it attempts to ascertain if the constitutional principles or rights said to be extinguished or eroded by the NSCA are really embodied in the FC and, if so, the extent to which they are a part the founding document. Next, it critically examines the provisions of the NSCA to determine the extent, if any, to which they represent a new assault on constitutional rights or principles. In line with this, this study provides a comprehensive overview on the NSCA using a purely doctrinal research method where key documents comprising the NSCA, the FC and the principles of the Rule of Law are analysed.