There must be ongoing training of existing teachers and support for professional development, including the provision of paid study leave. Article 13(2)(e) of the ICESCR requires States continuously to improve the material conditions of teaching staff. Notwithstanding this obligation, the CESCR has noted that in practice the general working conditions of teachers have deteriorated, and reached unacceptably low levels, in many States in recent years. Not only is this inconsistent with article 13(2)(e), but it is also a major obstacle to the full realisation of students’ right to education.402 Minimum education standards Governments must regulate education by setting and enforcing minimum standards to which all educational institutions must conform.403 All persons, especially those most disadvantaged and vulnerable, have the right as a minimum to receive a good quality basic education which focuses on the whole person and is adaptable to individual needs. Therefore, the State must identify appropriate quality standards for all levels of education and review and update these periodically. Article 13(3) requires States to have respect for the liberty of parents and legal guardians to choose other than public schools for their children, provided the schools conform to such “minimum educational standards” as may be laid down or approved by the State. The complementary provision article 13(4) affirms “the liberty of individuals and bodies to establish and direct educational institutions”, provided the institutions conform to the educational objectives set out in article 13(1) and minimum standards laid down by the State. Minimum standards may relate to issues such as admission, curricula and the recognition of certificates and must be consistent with the educational objectives set out in article 13(1).404 402 CESCR General Comment No. 13: The right to education E/C.12/1999/10 8 December 1999 at para 27. 403 Preliminary Report of the Special Rapporteur on the right to education E/CN.4/1999/49 13 January 1999 at paras 25 and 62. 404 CESCR General Comment No. 13: The right to education E/C.12/1999/10 8 December 1999 at para 29. 128