Explainer: what is the challenge to Bob Day's Senate seat all about?

Family First Senator Bob Day has resigned from the Senate, but controversy now rages about whether or not he was validly elected. The argument is that he was disqualified under Section 44(v) of the Constitution for holding an indirect pecuniary interest in an agreement with the Public Service. This matter concerns whether Day had such an interest in a contract with the Commonwealth.

The facts involved remain unclear, and it is hard to judge whether or not a breach of s 44(v) is likely to have occurred. It is especially difficult because his interest in the agreement was only indirect. The one High Court authority on the issue, the Webster case, is a judgment of a single judge back in 1975.

As it is quite old and has been the subject of much criticism, it is unknown whether the High Court would follow it or develop different criteria for determining what is a disqualifying pecuniary interest.

Why does it make a difference, given that Senator Day has resigned from the Senate?

Normally such cases are brought for the purpose of removing a person from the Senate.

The answer in this case is that it makes a difference in relation to who is chosen to replace him in the Senate. This is a particularly sensitive issue in a Senate that the government does not control.

If Senator Day was validly elected on July 2, 2016 and then resigned his seat in November 2016, section 15 of the Constitution would apply. It states that where the place of a senator becomes vacant before the expiration of his term of service, his replacement is chosen by the houses of parliament of the state from which he was chosen, in a joint sitting. So the South Australian parliament would choose Senator Day’s replacement.

Section 15 was amended in 1977 to make it clear that the South Australian parliament can only choose a person from the same party to which the outgoing senator belonged at the time of his or her election. The rationale is that if the people vote for a representative of one party, the replacement of that senator should come from the same party. So it would be up to the Family First party to nominate their choice of senator, which the South Australian parliament, in a joint sitting, would then formally choose.

During the period of the Whitlam government, there had been some fudging of the convention about appointing a person from the same party. For example, the Queensland Parliament appointed Albert Field to fill a Senate seat vacated by a Labor member. Field was technically a member of the Labor Party, but was opposed to the Whitlam government.

In order to avoid this type of problem, the Constitution was amended so that if a person is appointed from the relevant political party, but then expelled from that party before taking up his or her seat, he or she “shall be deemed not to have been so chosen”. This means that the party effectively chooses a senator’s replacement where there is a casual vacancy.

What if Senator Day was not validly elected?

If Senator Day was never validly elected at the July 2016 election, then it is more complicated. In the past, the High Court has resolved the issue by ordering a re-count of the vote, distributing the votes as if the disqualified senator did not exist. This usually means that it is the next person on the party’s ticket who is elected. On this basis, the second person on the Family First ticket in South Australia would most likely be elected.

This is complicated on this occasion, however, by two factors. First, it is possible that there are enough “below the line” votes for Senator Day personally that then went to different candidates, rather than the second Family First candidate, to alter the outcome.

Secondly, there would be doubts about the validity of the “above the line” votes for Family First, because a party requires two candidates to register its ticket above the line. If Day was disqualified, this would mean there was only one. It would therefore be arguable that all the above the line votes for Family First would not be counted, with preferences instead being passed on to the candidates of the next party preferenced on each ballot paper.

This could result in Labor or One Nation picking up Senator Day’s seat. As the Senate voting laws have recently changed to an optional preferential above the line system – a system that Senator Day challenged in the High Court – we have no relevant precedent as to how his disqualification would affect the recount in these circumstances.

The time for challenging the validity of the election of a candidate has now expired. However, the houses of parliament can still refer to the High Court, sitting as a Court of Disputed Returns, any question concerning the validity of the election of a senator or member.

The government proposes to ask the Senate to make such a referral on Monday. If the Senate agrees, it will be up to the High Court to decide these difficult constitutional issues. One way or the other, the outcome will have an impact upon the composition of the Senate.

This article has been corrected to accurately reflect the pecuniary interest issue.