Sri Lanka is a Democratic Republic and a Unitary State which is governed by a semi-presidential system, with a mixture of a presidential system and a parliamentary system. Most provisions of the constitution can be amended by a two-thirds majority in parliament. The amendment of certain basic features such as the clauses on language, religion, and reference to Sri Lanka as a unitary state require both a two-thirds majority and approval in a nationwide referendum.

In common with many democracies, the Sri Lankan government has three branches

• Executive: The President of Sri Lanka is the head of state, the commander in chief of the armed forces; head of government, and is popularly elected for a five-year term. The President heads the cabinet and appoints ministers from elected members of parliament. The President is immune from legal proceedings while in office with respect to any acts done or omitted to be done by him or her in either an official or private capacity. Following passage of the 19^th amendment to the constitution in 2015, the President has two terms, which previously stood at no term limit.

• Legislative: The Parliament of Sri Lanka is a unicameral 225-member legislature with 196 members elected in multi-seat constituencies and 29 elected by proportional representation. Members are elected by universal suffrage for a five-year term. The president may summon, suspend, or end a legislative session and dissolve Parliament any time after four and a half years. The parliament reserves the power to make all laws. The president's deputy, the Prime Minister, leads the ruling party in parliament and shares many executive responsibilities, mainly in domestic affairs.

• Judicial: Sri Lanka's judiciary consists of a Supreme Court – the highest and final superior court of record, a Court of Appeal, High Courts and a number of subordinate courts. The highly complex legal system reflects diverse cultural influences. Criminal law is based almost entirely on British law. Basic Civil law derives from Roman law and Dutch law. Laws pertaining to marriage, divorce, and inheritance are communal. Due to ancient customary practices and/or religion, the Sinhala customary law (Kandyan law), the Thesavalamai, and Sharia law are followed in special cases. The President appoints judges to the Supreme Court, the Court of Appeal, and the High Courts. A judicial service commission, composed of the Chief Justice and two Supreme Court judges, appoints, transfers, and dismisses lower court judges.