The increasing popular resistance and violent township protests amid the 1980s forced the South African government to declare a State of Emergency. On 20 July 1985 President P.W. Botha announced that violence in the country showed that “ordinary law and order was inadequate”.
Botha declared a State of Emergency in thirty-six magisterial districts. Areas affected were the Eastern Cape and the Pretoria Witwatersrand Vereeniging (PWV) region. Three months later the Western Province was also declared to a State of Emergency. After the declaration of the State of Emergency scores of people were detained under the Internal Security Act.
The State of Emergency gave more power to the police, the military and the president. The government could implement curfews controlling the movement of all people and prevent the media from covering any unrest or entering an area declared as an area of unrest. The state of emergency also gave the president the power to rule by decree without the constraints of the constitution or parliament.
Source: South African History Online