The Internal Security Act 1960 (ISA) of Singapore is a statute that grants the executive power to enforce preventive detention, prevent subversion, suppress organized violence against persons and property, and do other things incidental to the internal security of Singapore. The present Act was originally enacted by the Parliament of Malaysia as the Internal Security Act 1960 (No. 18 of 1960), and extended to Singapore on 16 September 1963 when Singapore was a state of the Federation of Malaysia. Before a person can be detained under the ISA by the Minister for Home Affairs, the President must be satisfied that such detention is necessary for the purposes of national security or public order. In the landmark case of Chng Suan Tze v. Minister for Home Affairs (1988), the Court of Appeal sought to impose legal limits on the power of preventive detention by requiring the Government to adduce objective facts which justified the President's satisfaction. Two months after the decision, a series of legislative and constitutional amendments was enacted that effectively reversed the Chng Suan Tze decision. These amendments were subsequently confirmed to be valid by the High Court and Court of Appeal in Teo Soh Lung v. Minister for Home Affairs (1989–1990), which held it is sufficient for the President to be subjectively satisfied that a detainee is a threat to national security in order for a detention order to be issued under the ISA. Notable ISA cases include Operation Coldstore in 1963 which led to the arrest of some 100 left-wing politicians and trade unionists, including members of the socialist opposition party, the Barisan Sosialis. Chia Thye Poh, an alleged Communist, was detained and subject to other restrictions on his liberty under the ISA from 1966 to 1998. The Chng Suan Tze and Teo Soh Lung cases resulted from a 1987 security operation called Operation Spectrum in which 22 Roman Catholic church and social activists and professionals accused of being members of a Marxist conspiracy were detained under the ISA. The ISA also empowers the authorities to prohibit political and quasi-military organizations, ban subversive documents and publications, shut down entertainments and exhibitions that are or are likely to be detrimental to the national interest, and to suppress organized violence by declaring parts of Singapore to be security areas. History and developments British colonial Malaya introduced the Emergency Regulations Ordinance 1948 on 7 July 1948 during the Malayan Emergency