A crucial function of a constitution - and one of the classic features of democracies - is the division of power among the three pillars of government.

Constitutions protect democracy by separating state power into three arms. The legislature (parliament, the provincial legislatures and local councils) makes the laws and monitors the executive; the executive (the president, deputy president and ministers) makes policy, proposes laws and implements laws passed by the legislature; and the judiciary tries cases and administers justice.

The judiciary is unique in that it is not elected, but is independent. This means no one can interfere in the work of the Constitutional Court and the other courts in the country.

In practice this means each arm of the state keeps watch over the power of the others. The courts can judge the actions of the legislature and the executive but cannot pass laws. The legislature can make laws but cannot hand down judgments or take executive action.

It's not easy to keep these in balance. Often the challenge is to ensure that the executive does not wield its authority without being contained by the other branches.