Party-hopping is becoming a pretty common occurrence in Australian federal politics. The last time the Reps managed to complete a term without anyone quitting or being kicked out of their party in either house was way back in 1983-4, and that was a term with more than a year lopped off it by an early election. Since then there's been an average of three defections/expulsions per term, with the last four terms scoring four, eight, four and so far five, and the five seems about to be six.
Genuinely interesting policy defections aren't abundant among the 42 I found in the last 40 years. This roughly annual event seems to most often happen as a result of internal tensions, especially in minor parties. Deselection and/or misbehaviour are also common triggers. There was a Voice policy dimension to the recent departures of Andrew Gee from the Nationals and Lidia Thorpe from the Greens, but both were isolated cases that did not turn into broader breakaway movements from the party. We now have at least the prospect (it could well happen tomorrow) that WA Senator Fatima Payman will leave the ALP, which will be a first case for the Australian federal party of an issue that has plagued its UK counterpart for years - losing or deciding to lose MPs for their positions re the Middle East.
If Payman leaves the party this will be the first defection from the Government in this term. For comparison the Hawke/Keating government lost by my count just two MPs in 13 years, the first of them coming after ten years being Keith Wright who was kicked out after recontesting as an independent after being disendorsed. The Howard government had three defections even not counting Pauline Hanson in its first term, another in its third and an internal party-switch in its fourth. The Rudd/Gillard government's only casualty was Craig Thomson, while the Abbott/Turnbull/Morrison government had six in nine years (Jensen, Bernardi, Banks, Kelly, McMahon and tokenly Christensen).
