The proposed "civil solidarity pact", or Pacs, has been fiercely resisted by centre-right parties, who say it is an assault on the family and a stalking horse for wider gay rights.
The first attempt to table the draft law was destroyed by a parliamentary manoeuvre in October, to the embarrassment of Lionel Jospin's centre- left government. The second, last month, became bogged down in amendments and filibustering.
The third attempt - due to go to a vote a week today - has become a politically and psychologically crucial test of the solidarity and competence of Mr Jospin's coalition. The centre-right will try to destroy the plans through a kind of legislative acupuncture. More than 1,000 amendments have been tabled and more than 700 had still to to be heard last night.
The Pacs would give unmarried couples broadly equivalent rights on inheritance, tax, health and tenancy as those granted to married couples. The concept has already coined a new French verb: "pacser". (As in, "Voulez-vous pacser avec moi?")
Originally, it was conceived as a partial answer to demands by homosexual pressure groups for a form of legally recognised marriage ceremony. To avoid homophobic attacks, the Jospin government watered down and broadened the concept to include heterosexual couples.
This opened another front of attack, from the Catholic Church and family lobbies, who fear the Pacs could confirm a trend against marriage among the young. They say the Pacs would give people all the advantages of marriage without the constraints, and leave children of Pacs couples in a social and legal no-man's-land.
Most of all, the battle has been an occasion for an outpouring of homophobic prejudice - and not all of it from the Right. The plans were defeated at the first attempt because many left-wing deputies, facing anti-Pacs propaganda in their constituencies, failed to turn up.Reuse content