any racial or religious community. If approved by the council, the bill will be presented for the president's assent. The last stage involves the granting of assent by the president, before the bill officially becomes a law. Constitution The Constitution of Singapore is the supreme law of Singapore and it is a codified constitution. The constitution cannot be amended without the support of more than two-thirds of the members of parliament on the second and third readings. The president may seek opinion on constitutional issues from a tribunal consisting of not less than three judges of the Supreme Court. Singaporean courts, like the courts in Australia, cannot offer advisory opinion on the constitutionality of laws. Part IV of the constitution guarantees the following: liberty of a person prohibition of slavery and forced labour protection against retrospective criminal laws and repeated trials equal protection prohibition of banishment and freedom of movement freedom of speech, assembly and association freedom of religion right to education The sections on liberty of the person and freedoms of speech, assembly, movement, association and religion are all qualified by allowing Parliament to restrict those freedoms for reasons including national security, public health, and "public order or morality". In practice, the courts have given complete discretion to the government in imposing such restrictions. Part XII of the constitution allows the Parliament of Singapore to enact legislation designed to stop or prevent subversion. Such legislation is valid even if it is inconsistent with Part IV of the constitution. The Internal Security Act (ISA) is a legislation under such provision. In 1966, Chia Thye Poh was detained under the ISA and was imprisoned for 23 years without trial. Afterwards, he was placed under conditions of house arrest for another nine years. Judiciary Elections and political parties Voting has been compulsory in Singapore since 1959 and there is universal suffrage. The legal voting age is 21. The Elections Department of Singapore is responsible for the planning, preparation and conduct of presidential and parliamentary elections and of any national referendum in Singapore. It is a department under the Prime Minister's Office. Paper ballots are still used in Singapore. However, there is a concern that voting secrecy might be compromised as ballot papers have serial numbers on them. As stated in the Elections Department website: ballot papers can be examined only under strict conditions, and there are safeguards that make it extremely difficult