EUROPE
In a number of countries in Europe, the status of "registered partnership" has been established.
In 1989, Denmark became the first country to institute legislation granting registered same-sex partners the same rights as married couples. Church weddings are not allowed.
Norway, Sweden and Iceland all enacted similar legislation in 1996, and Finland followed suit six years later.
The Netherlands became the first country to offer full civil marriage rights to gay couples in 2001.
In neighbouring Belgium gay marriages were allowed in 2003.
In June 2005, Spanish MPs voted in favour of allowing gay couples to marry and adopt children. The bill is set to become law in July.
The lower house was able to overrule the Senate, which rejected the bill.
Germany has allowed same-sex couples to register for "life partnerships" since 2001. The law only gives couples the same inheritance and tenants' rights as heterosexual married couples.
France in 1999 introduced a civil contract called the Pacs, which gives some rights to cohabiting couples, regardless of sex. These do not include the full rights of marriage, notably over taxes, inheritance and adoption. In 2004, a mayor conducted the country's first gay marriage, but it was later nullified by a court.
In Luxembourg, a law on civil partnerships largely inspired by the French model was introduced in 2004.
In Britain, legislation due to come into force in December 2005 will give same-sex couples in registered partnerships similar rights to married couples, in areas such as pensions, property, social security, and housing.
CANADA
In June 2005, Canada's parliament approved a bill to legalise same-sex marriage. It is expected to win Senate approval and become law by July, making Canada the third country after the Netherlands and Belgium to allow gay marriages. Gay marriage is already legal in eight of 10 provinces and one of Canada's three territories.
NEW ZEALAND
In December, 2004, New Zealand's parliament passed controversial legislation to recognise civil unions between gay couples.
THE UNITED STATEs
"ONE NATION UNDER GOD"
Many states have passed amendments to their constitutions defining marriage as the union of a man and a woman. Congress has failed to approve a similar amendment to the US constitution.
President George W Bush has made clear that he supports such an amendment.