In late 1987, Zimbabwe's parliament amended the constitution. On 30 December it declared Mugabe to be executive President, a new position that combined the roles of head of state, head of government, and commander-in-chief of the armed forces. This position gave him the power to dissolve parliament, declare martial law, and run for an unlimited number of terms. According to Meredith, Mugabe now had "a virtual stranglehold on government machinery and unlimited opportunities to exercise patronage". The constitutional amendments also abolished the twenty parliamentary seats reserved for white representatives, and left parliament less relevant and independence.

More Info: en.m.wikipedia.org