Just a month after electing a new president, France votes again this Sunday in the first round of elections for the National Assembly, the lower house of the French Parliament.

The Parliament (there is also a much less powerful Senate) performs a somewhat different role to ours, since the president is independently powerful, but in electoral terms it is very similar — more so than countries we are more likely to compare ourselves with, such as Britain, Canada or the US.

Members of the National Assembly represent single-member districts, averaging about 75,000 voters each, or about the same size as those in our House of Representatives. (France being a more populous country, there are more of them — 577.) As in most democracies, voting is optional; turnout in 2002 was about 65%, much lower than for presidential elections.

There are no preferences, but if no candidate in a seat wins a majority in the first round, a second round of voting is held a week later between the top two candidates, approximating the effect of a preferential system. Last time a run-off was required in about 90% of seats. A third or even fourth candidate can also go through to the second round, provided their vote exceeds 12.5% of the total enrolment (this is unusual, but happens in a few seats).

Elections are, therefore, more representative than under first-past-the-post voting, but like any single-member system it is unfair in two obvious ways. Majorities tend to be lopsided; the ruling centre-right UMP won a large majority (356 seats) last time with about a third of the vote. And minor parties whose vote is evenly spread get shafted: especially the far-right National Front, which won 11.3% of the vote in 2002 but no seats at all. (Adam Carr’s Psephos has complete results.

This time, the new President,  Nicolas Sarkozy, is seeking a majority to carry out his reformist program. A hostile majority in the National Assembly, as has happened three times since 1986, would severely limit the President’s authority. So France provides a test of the theory that voters consciously choose to “balance” different elements in government, to prevent concentration of power.

The evidence is pretty overwhelming that they do not. With only one exception, every time legislative elections have been held immediately after a presidential election, the President’s party has won a clear majority. Every indication is that the same will happen this time: the UMP is polling between 7% and 10% better than its 2002 result.

Whatever other problems Sarkozy might run into, it doesn’t look as if he will have to worry about control of Parliament.