Arthur Goldhammer’s excellent blog on French politics and society points to this article on the French pact civil de solidarité – a kind of civil union introduced in 1999/2000, largely as an alternative to gay marriage. But the pacs has had very interesting consequences for straight couples (95% of couples with pacs are straight), as this chart shows.
The growth of the pacs’ popularity over its first decade is striking. There are now two pacs for every three marriages. Interestingly, this is because of both a significant decline in marriage, and a significant increase in the overall number of people willing to engage in some kind of state-sanctioned relationship. While you would obviously need more finely grained data to establish this properly, the obviously intuitive interpretation of this (at least to me) is that the pacs have grown both by providing an option for people who would probably not have gotten married in the first place, and attracted a number of people who otherwise would have gotten married, but who prefer the pacs’ lower level of formality (it is much easier to cancel a pacs relationship than to get divorced). Perhaps this provides grist for the mills of social conservatives (who could claim, stretching the data a bit, that gay-appeasing civil unions are undermining the sacred institution of marriage) – but it would oblige them to face up to the question of whether they should prefer gay marriage to potentially corrosive civil unions that straight couples can take advantage of too. Liberals and leftwingers don’t face nearly the same dilemma, since they can reasonably assume that those who choose civil unions over marriage have good reason for doing so (and perhaps will get married later if they want to; obviously, you can’t tell from data like this how many partners in pacs decide to get married later on).