Section 46 gives any Australian, regardless of position or title, the authority to sue any fraudulently sitting member of parliament!
"46 Penalty for sitting when disqualified
Until the Parliament otherwise provides, any person declared by this Constitution to be incapable of sitting as a senator or as a member of the House of Representatives shall, for every day on which he so sits, be liable to pay the sum of one hundred pounds to any person who sues for it in any court of competent jurisdiction."
