| Country | Legal system |
| Sierra Leone | based on English law and customary laws indigenous to local tribes; has not accepted compulsory ICJ jurisdiction |
| Singapore | based on English common law; has not accepted compulsory ICJ jurisdiction |
| Slovakia | civil law system based on Austro-Hungarian codes; accepts compulsory ICJ jurisdiction with reservations; legal code modified to comply with the obligations of Organization on Security and Cooperation in Europe (OSCE) and to expunge Marxist-Leninist legal theory |
| Slovenia | based on civil law system; has not accepted compulsory ICJ jurisdiction |
| Solomon Islands | English common law, which is widely disregarded; has not accepted compulsory ICJ jurisdiction |
| Somalia | no national system; a mixture of English common law, Italian law, Islamic Shari'a, and Somali customary law; accepts compulsory ICJ jurisdiction with reservations |
| South Africa | based on Roman-Dutch law and English common law; has not accepted compulsory ICJ jurisdiction |
| South Georgia and the South Sandwich Islands | the laws of the UK, where applicable, apply; the senior magistrate from the Falkland Islands presides over the Magistrates Court |
| Southern Ocean | void |
| Spain | civil law system, with regional applications; accepts compulsory ICJ jurisdiction with reservations |
| Spratly Islands | void |
| Sri Lanka | a highly complex mixture of English common law, Roman-Dutch, Kandyan, and Jaffna Tamil law; has not accepted compulsory ICJ jurisdiction |
| Sudan | based on English common law and Islamic law; as of 20 January 1991, the now defunct Revolutionary Command Council imposed Islamic law in the northern states; Islamic law applies to all residents of the northern states regardless of their religion; however, the CPA establishes some protections for non-Muslims in Khartoum; some separate religious courts; accepts compulsory ICJ jurisdiction with reservations; the southern legal system is still developing under the CPA following the civil war; Islamic law will not apply to the southern states |
| Suriname | based on Dutch legal system incorporating French penal theory; accepts compulsory ICJ jurisdiction with reservations |
| Svalbard | the laws of Norway, where applicable, apply |
| Swaziland | based on South African Roman-Dutch law in statutory courts and Swazi traditional law and custom in traditional courts; accepts compulsory ICJ jurisdiction with reservations |
| Sweden | civil law system influenced by customary law; accepts compulsory ICJ jurisdiction with reservations |
| Switzerland | civil law system influenced by customary law; judicial review of legislative acts, except with respect to federal decrees of general obligatory character; accepts compulsory ICJ jurisdiction with reservations |
| Syria | based on a combination of French and Ottoman civil law; Islamic law is used in the family court system; has not accepted compulsory ICJ jurisdiction |
| Taiwan | based on civil law system; has not accepted compulsory ICJ jurisdiction |
| Tajikistan | based on civil law system; no judicial review of legislative acts; has not accepted compulsory ICJ jurisdiction |
| Tanzania | based on English common law; judicial review of legislative acts limited to matters of interpretation; has not accepted compulsory ICJ jurisdiction |
| Thailand | based on civil law system, with influences of common law; has not accepted compulsory ICJ jurisdiction |
| Timor-Leste | UN-drafted legal system based on Indonesian law remains in place but is to be replaced by civil and penal codes based on Portuguese law; these have passed but have not been promulgated; has not accepted compulsory ICJ jurisdiction |
| Togo | French-based court system; accepts compulsory ICJ jurisdiction, with reservations |