In 1993 New Zealanders voted in a referendum to change their voting system from the traditional first-past-the-post (FPP) method to Mixed Member Proportional representation (MMP). How, and why, did this dramatic change come about?

The origins of electoral reform lay in the gradual breakdown of public trust and confidence in politicians, Parliament, and the simple certainties of the old two-party system. This process began in the 1950s and 1960s and gathered momentum in the 1970s and 1980s, decades marked by economic uncertainty and the emergence of new social and political movements.

Criticism of the voting system intensified after the 1978 and 1981 elections. On each occasion the Labour opposition actually secured more votes overall than National, but the latter won more seats in Parliament and remained in government.

Disillusioned with both National and Labour, more and more voters began to look to alternative parties. But the FPP system did them no favours. Social Credit, the leading 'third' party since 1954, won 16% of the overall vote in 1978 but only one seat out of the 92 in Parliament. Three years later nearly 21% of electors voted for Social Credit, but the party gained just two seats. In the 1984 election the New Zealand Party won 12% but no seats.

As critics pointed out, the FPP system tended to create Parliaments quite different in composition to those that the voters appeared to want. The answer, some people argued, was a system of proportional representation - in which each party's share of the seats in Parliament would be close to its share of the overall vote.

The Royal Commission

During the 1981 and 1984 campaigns Labour promised to set up a Royal Commission to look into a wide range of issues relating to the electoral system. Following Labour's victory in the latter election, a Royal Commission on the Electoral System was duly established in early 1985.

Its report, completed in December 1986, was surprisingly radical. It recommended New Zealand adopt the German-style MMP system, in which each elector would get two votes, one for an electorate MP and one for a party. The size of Parliament would increase to 120 MPs: half would be elected in single-member constituencies (as before); the other half would be selected from party lists so that in general each party's share of all 120 seats corresponded to its share of the overall vote.

Few of Labour's leaders welcomed the Commission's recommendations, however, and the government tried to sideline the issue. Although National's leadership also disliked the idea of MMP, they saw an opportunity to embarrass the government over its failure to respond to the Commission's proposals. As each party tried to outmanoeuvre the other, both entered the 1990 election campaign promising to hold referenda on electoral reforms that they did not really want.

The Labour government was heavily defeated in the 1990 election, but its National successor was soon under fire for breaking election promises. Confidence and trust in politicians and Parliament plunged to new depths. Polls showed that politicians ranked alongside used-car salespeople as the least-respected occupational group in the country. Public support for radical electoral reform began to grow.

'The People Screamed'

The National government agreed to hold an 'indicative' referendum (that is, one that was not 'binding' on the government) in September 1992.

In a complicated two-part poll, voters were asked whether they wanted to change the existing voting system, and then to indicate support for one of four reform options: MMP, the Single Transferable Vote (STV), Supplementary Member (SM) or Preferential Vote (PV). If there was majority support for change, the government promised to hold a binding referendum (with a choice between FPP and the most popular reform option) the following year.

Although only 55% of electors took part, an overwhelming 85% voted to change their electoral system. In the second part of the poll, 70% favoured MMP. As Labour leader Mike Moore put it: 'The people didn't speak on Saturday. They screamed.'

The second, binding referendum - a straight run-off between FPP and MMP - was held at the same time as the 1993 general election. There were now lobby groups on both sides of the debate, and the campaign was fiercely contested. The turnout was much higher - 85% - and the result much closer than in 1992. But MMP was still backed by a comfortable margin, 54% to 46%. New Zealand was to have a new voting system.

Into the Unknown: 1996 and Beyond

The next three years, before the first MMP election in 1996, was a period of transition and uncertainty. The main parties tried to re-position themselves for the new environment and a number of new parties emerged.

Electoral rules and procedures were overhauled and in 1995 the boundaries of the 60 general and five Maori electorates were finalised. Electoral officials (especially the newly established Electoral Commission) also initiated a massive publicity campaign to inform voters about the new system.

The 1996 election produced a close and indecisive result. After two months of negotiations a coalition government was formed (to the surprise of many) between the previously hostile National and New Zealand First parties. Subsequent events - in particular a spate of defections (or 'party-hopping') by MPs and the messy collapse of the coalition - sapped public confidence in the new voting system, but support for MMP has rallied in more recent years.

As the Royal Commission and pro-MMP campaigners had predicted, Parliament has become much more diverse and representative of modern New Zealand society - in 2006 39 women, 21 Maori, four Pacific Islanders, and two Asian MPs are among the 121 MPs.