The Expected "Super Saturday" By-Elections

Today's four resignations from the House of Representatives following the Section 44 disqualification of Labor Senator Katy Gallagher is expected to trigger a day of at least five by-elections, or at least a cluster of by-elections close to each other.  The following seats are affected:

Braddon, TAS (ALP, 2.2%)
Fremantle, WA (ALP, 7.5%)
Longman, QLD (ALP, 0.8%)
Mayo, SA (Centre Alliance vs Lib, 5.0%; Lib vs ALP 5.4%)
Perth, WA (ALP, 3.3%) 

See The Tally Room for detailed histories of these seats.  Also see the Poll Bludger thread for Perth.  All seats will be contested on the old boundaries, irrespective of redistributions.

It's possible that given the strictness of the High Court's ruling, other MPs may come under pressure to resign or be referred to the High Court (note: as of Friday the media are suddenly all over the Anne Aly story, which has been known via Jeremy Gans' Twitter comments for months), though the Coalition may not be in any great hurry to hunt down any more and invite more scrutiny of its own remaining unclear cases.  The by-elections are not just a nuisance for Labor, but also for the Coalition, which must either throw resources into contesting them seriously or else chicken out and leave voters wondering what all the fuss was about.

Australia has never had a day with five federal by-elections before, so it would be quite a novelty.  Three were held on the same day in 1981 and 1984.  In 1994 four were held across three weekends following a cluster of resignations, but the resignations came on different days.  At state level, NSW has often held multiple by-elections on the same day.