This means that Congress cannot be dissolved, and that "snap elections" as understood under the parliamentary system cannot be invoked. However, during the presidency of Ferdinand Marcos, the constitution starting from 1973, and first applied in 1978, placed the country under the semi-presidential system of government, where the Batasang Pambansa (parliament) can be dissolved. During the operation of that constitution, the parliament was not dissolved, but Marcos, who had earlier been elected in 1981 for a six-year term, asked parliament to move the 1987 presidential election to 1986, in response to growing social unrest, political and economic crises, political instability, and deteriorating peace and public order.