88 unconditionally the declaration of invalidity for any period to allow the competent authority to correct the defect. 8.15 Inherent powers of Constitutional Court, Supreme Court and High Court The Constitutional Court, the Supreme Court and the High Court have inherent power to protect and regulate their own process and to develop the common law or the customary law, taking into account the interests of justice and the provisions of this Constitution. PART 2 APPOINTMENT AND TENURE OF MEMBERS OF JUDICIARY 8.16 Qualifications of judges of Constitutional Court (1) A person is qualified for appointment as a judge of the Constitutional Court if he or she is a citizen of Zimbabwe, is at least forty years old and has a sound knowledge of constitutional law and, in addition, possesses one of the following qualifications— (a) he or she has been a judge of a court with unlimited jurisdiction in civil or criminal matters in a country in which the common law is Roman-Dutch or English, and English is an official language; or (b) for at least twelve years, whether continuously or not, he or she has been qualified to practise as a legal practitioner— (i) in Zimbabwe; or (ii) in a country in which the common law is Roman-Dutch or English and English is an official language; and is currently so qualified to practise. (2) To be appointed as a judge of the Constitutional Court a person must be a fit and proper person to hold office as a judge. 8.17 Qualifications of judges of Supreme Court (1) A person is qualified for appointment as a judge of the Supreme Court if he or she is a citizen of Zimbabwe and at least forty years old and, in addition— (a) is or has been a judge of a court with unlimited jurisdiction in civil or criminal matters in a country in which the common law is Roman-Dutch or English and English is an official language; or (b) for at least ten years, whether continuously or not, he or she has been qualified to practise as a legal practitioner— (i) in Zimbabwe; or (ii) in a country in which the common law is Roman-Dutch or English and English is an official language; and is currently so qualified to practise.