Kate O'Regan served in the Constitutional Court of South Africa from its inception in 1995 until her retirement in 2009.
| No. | Case name | Citation | Notes | |
|---|---|---|---|---|
| 1 | S v Bhulwana; S v Gwadiso | 1995. ZACC. 11. | Unanimous. | |
| 2 | Besserglik v Minister of Trade, Industry and Tourism | 1996. ZACC. 8. | Unanimous. | |
| 3 | Scagell v Attorney-General, Western Cape | 1996. ZACC. 18. | Unanimous. | |
| 4 | Tsotetsi v Mutual and Federal Insurance Company | 1996. ZACC. 19. | Unanimous. | |
| 5 | Prinsloo v Van der Linde | 1997. ZACC. 5. | Co-written with Ackermann and Sachs. | |
| 6 | ANC v Minister of Local Government and Housing, KwaZulu-Natal | 1998. ZACC. 2. | Unanimous. | |
| 7 | Fedsure Life Assurance v Greater Johannesburg Transitional Metropolitan Council | 1998. ZACC. 17. | Co-written with Chaskalson and Goldstone. | |
| 8 | Premier v Association of Governing Bodies of State Aided Schools | 1998. ZACC. 20. | Unanimous. | |
| 9 | South African National Defence Union v Minister of Defence | 1999. ZACC. 7. | ||
| 10 | Veerasamy v Engen Refinery | 2000. ZACC. 7. | Unanimous. | |
| 11 | Dawood v Minister of Home Affairs | 2000. ZACC. 8. | Unanimous. | |
| 12 | Department of Education, Eastern Cape v Ed-U-College | 2000. ZACC. 23. | Unanimous. | |
| 13 | Fredericks v MEC for Education and Training, Eastern Cape | 2001. ZACC. 6. | Unanimous. | |
| 14 | S v Bierman | 2002. ZACC. 7. | Unanimous. | |
| 15 | Khumalo v Holomisa | 2002. ZACC. 12. | Unanimous. | |
| 16 | National Union of Metal Workers of South Africa v Bader Bop | 2002. ZACC. 30. | Unanimous. | |
| 17 | Satchwell v President | 2003. ZACC. 2. | Unanimous. | |
| 18 | S v Basson | 2004. ZACC. 13. | Co-written with Ackermann, Madala, Mokgoro, Moseneke, and Ngcobo. | |
| 19 | Bato Star Fishing v Minister of Environmental Affairs and Tourism | 2004. ZACC. 15. | Dual opinions with Ngcobo; unanimous. | |
| 20 | Mabaso v Law Society of the Northern Provinces | 2004. ZACC. 8. | Unanimous. | |
| 21 | Rail Commuters Action Group v Transnet | 2004. ZACC. 20. | Unanimous. | |
| 22 | K v Minister of Safety and Security | 2005. ZACC. 8. | Unanimous. | |
| 23 | African Christian Democratic Party v Electoral Commission | 2006. ZACC. 1. | Unanimous. | |
| 24 | South African Liquor Traders Association v Chairperson, Gauteng Liquor Board | 2006. ZACC. 7. | Unanimous. | |
| 25 | Giddey v JC Barnard and Partners | 2006. ZACC. 13. | Unanimous. | |
| 26 | South African Broadcasting Corporation v National Director of Public Prosecutions | 2006. ZACC. 15. | Co-written with Langa, Kondile, Madala, Nkabinde, Van Heerden and Yacoob. | |
| 27 | South African National Defence Union v Minister of Defence | 2007. ZACC. 10. | Unanimous. | |
| 28 | S v Shaik | 2008. ZACC. 7. | Unanimous. | |
| 29 | Richter v Minister of Home Affairs | 2009. ZACC. 3. | Unanimous. | |
| 30 | Lufuno Mphaphuli & Associates v Andrews | 2009. ZACC. 6. | ||
| 31 | Mazibuko v City of Johannesburg | 2009. ZACC. 28. | Unanimous. |