The current edit is also incorrect. It reads as follows: 

 "This constitutional separation between the Executive Branch and the Legislative Branch is quite different from the British, Canadian, or Australian parliamentary cabinet systems, where the members of the Cabinet are required by long-standing precedents to be sitting members of the legislature." 

 As stated above, there is no requirement in the Westminster system for Cabinet members to be sitting members of the legislature. It's only a conventionand not a constitutional one: In Canada, Michael M. Fortier was sworn in as Minister of Public Works and Government Services on February 6, 2006, without having been elected or appointed to Parliament.