Constitution of Australia
Note: The convention was written into the Constitution after the national referendum of 1977. The change means a new Senator has to be from the same party as the old one. This would have prevented the appointment by Lewis, but not that by Bjelke-Petersen. However, the change also says that if "before taking his seat [the chosen Senator] ceases to be a member of that party...he shall be deemed not to have been so chosen or appointed".  Bjelke-Petersen appointee Albert Patrick Field was expelled from the Labor Party before taking his seat and would not have been appointed under the changed Constitution.