OPINION: In a democracy, voters should determine who is elected to Parliament. The Senate electoral system fails this test. Design flaws mean that people can elect candidates they do not support. This follows from the "above the line" voting system used for the Senate. Once a person has selected the party of their choice, they lose control of their vote. Preferences are not allocated by the voter, but as directed by the party.

People can avoid this, but only by following the alternate "below the line" voting system, in which every candidate must be ranked. This is so difficult and time-consuming that almost no one casts a ballot in this way. At the 2013 election for NSW Senate representatives, the below the line voting system required electors to rank 110 candidates.

The combined effect of the above and below the line voting systems is to place enormous power in the hands of party officials. They can seek electoral advantage by entering into backroom deals with other parties. This can involve the transfer of a voter's preferences across political lines. For example, a person voting 1 for Labor may elect someone from the Family First Party, or a person seeking to allow development in national parks may end up electing a climate change activist.

This is not a new problem. The system has operated since 1984, but little has been made of it because it suited the interests of the major parties. This changed at the 2013 election when it became clear that smaller parties could exploit the system.

The 2013 election saw a metre long ballot paper in NSW (complete with a magnifying glass) and a profusion of micro parties around the nation. These micro parties proved adept at winning small numbers of first preference votes, which were then aggregated between them to give one of their number a shot at election. The result was a lottery in which a party securing a tiny first preference vote could win a seat in the Senate.

Many have since grappled with how the system should be reformed. Last week, the government finally grasped the nettle and introduced the Commonwealth Electoral Amendment Bill into Parliament. In all but one respect, it amounts to a major improvement on the current law.

Most importantly, the change will allow voters, and not parties, to determine the flow of preferences in Senate elections. It will do this by permitting voters to exercise an optional preferential vote in numbering parties above the line. They will be asked to order at least six parties, and preferences will not flow beyond their selection. Where a person fails to number this many boxes, their vote will still be counted so long as they have indicated a preference for at least one party.

The problem with the bill is that fails to also reform the below the line voting system. This will be left as a full preferential system, which means that voters must still rank every candidate.

Consequently, voting for candidates would continue to be far more onerous than voting for political parties. There would be no easy way for a person to, for example, choose the second candidate listed by a party, rather than the first. Indeed, few people are likely to vote below the line, thereby preserving the power of factions and groups within major parties to control which of their candidates are elected.

The driving logic behind the bill is that voters and not parties should determine electoral outcomes. This requires the government to go further and reform below the line voting for candidates. Voters must be given a straightforward means of choosing between the candidates put forward by a political party.

Without this, the bill is open to attack on the basis that it privileges the interests of some parties over others. Disturbingly, it creates the impression that it is designed to harm the electoral chances of minor parties while retaining the capacity of major parties to manipulate the preferences of voters through the ordering of candidates.

There is an easy remedy. In addition to recommending above the line optional preferential voting, the parliamentary inquiry into the system also proposed that voters at a normal half-Senate election have the alternative of numbering just six or more candidate boxes below the line. This second recommendation should be adopted.

Unfortunately, there is little time for the bill to be fixed. It was introduced into Parliament last week and immediately referred to the Joint Standing Committee on Electoral Matters. Submissions on the bill close Monday. Public hearings will be held on Tuesday, at which witnesses including myself will appear. The committee will then deliver its report on Wednesday. It can only be hoped that the few days available will produce a reformed Senate voting process that genuinely reflects the will of the people.

George Williams is the Anthony Mason Professor of Law at UNSW. Twitter: @ProfGWilliams

This opinion piece was first published in the Sydney Morning Herald.