3. Matters falling under the exclusive competence of the Parliament, the Government and the Courts as defined by the Constitution shall not be the subject of a referendum. 4. A referendum shall only be binding where the number of voters is higher than half of the registered electors . 5. The process of a referendum shall be defined by law. Section 67 (Organs of Sovereignty) The organs of sovereignty shall comprise the President of the Republic, the National Parliament, the Government and the Courts. Section 68 (Incompatibilities) 1. The holding of the offices of President of the Republic, Speaker of the National Parliament, President of the Supreme Court of Justice, President of the High Administrative, Tax and Audit Court, Prosecutor-General and member of Government shall be incompatible with one another. 2. The law shall define other incompatibilities. Section 69 (Principle of separation of powers) Organs of sovereignty, in their reciprocal relationship and exercise of their functions, shall observe the principle of separation and interdependence of powers established in the Constitution. Section 70 (Political parties and the right of opposition) 1. Political parties shall participate in organs of political power in accordance with their democratic representation based on direct and universal suffrage. 2. The right of political parties to democratic opposition, as well as the right to be informed regularly and directly on the progress of the main issues of public interest, shall be recognised. Section 71 (Administrative organisation)