| Year | Number [1] | Authority | 
| 1901 | 7 | Constitution, s. 65 | 
| 1915 | 8 | Ministers of State Act 1915 | 
| 1917 | 9 | Ministers of State Act 1917 | 
| 1935 | 10 | Ministers of State Act 1935 | 
| 1938 | 11 | Ministers of State Act 1938 | 
| 1941 | 19 | Ministers of State Act 1941 [2] | 
| 1951 | 20 | Ministers of State Act 1951 [3] | 
| 1956 | 22 | Ministers of State Act 1956 | 
| 1964 | 25 | Ministers of State Act 1964 | 
| 1967 | 26 | Ministers of State Act 1967 | 
| 1971 | 27 | Ministers of State Act 1971 | 
| 1987 | 30 | Ministers of State Amendment Act (No. 2) 1987 | 
| 2000 | 42 [4] | Ministers of State and Other Legislation Amendment Act 2000 |