It’s been a week of rainbows for gay marriage activists around the world, with the leader of the free world pledging his support, the New Zealand prime minister echoing it and Argentinean president Cristina Fernandez de Kircher set to write Prime Minister Julia Gillard a letter to encourage her to support gay marriage, after two Australians became the first foreign same-s-x couple to wed in Buenos Aires.

Crikey takes a look around the globe to see what countries allow same-sex marriage and how world leaders have responded.

The countries that allow it:

  • The Netherlands was the first country in the world to fully legalise same-sex marriage, when the Dutch Parliament passed a bill in 2000.
  • In 2003 Belgium became the second country to legalise gay marriage. The country initially only recognised gay marriages that were legally performed outside Belgium, but the following year permitted gay marriage as long as one spouse at lived in Belgium for a minimum of three months.
  • Canada became the third country to legalise gay marriage in 2005. Canadian prime minister Paul Martin said at the time that Canada had to pass the legislation because the country was a nation of minorities.
  • Shortly after Canada, Spain legalised same-sex marriage in 2005. Then Prime Minister José Luis Rodíguez Zapatero told parliament: “Today, Spanish society is responding to a group of people who have been humiliated, whose rights have been ignored, their dignity offended, their identity denied and their freedom restricted.”
  • In 2006 South Africa became the first African nation to embrace same-sex marriage. Despite homosexuality still being illegal in many countries on the African continent, the law was passed a year after the Constitutional Court deemed that denying gay couples marriage was unconstitutional.
  • Norway‘s parliament passed a same-sex marriage bill 84 to 41 in 2008. The legislation also allowed homosexual couples to adopt children and permitted lesbians being artificially inseminated.
  • In 2009 Sweden’s parliament passed a bill by a near-unanimous margin of 261 to 22 to allow same-sex marriage. Civil unions for gays had previously been legalised.
  • Portugal’s president Anibal Cavaco Silva, a practising Roman Catholic, put his personal beliefs aside and legalised gay marriage in 2010.
  • Johanna Sigurdardottir, Prime Minister of Iceland and the first openly gay head of state, presided over the unanimous 2010 vote in parliament to legalise gay marriage, 49 to zero.
  • Argentina became the first Latin American nation to legally recognise gay marriage, when President Cristina Fernandez de Kircher signed the bill into law in 2010. The president called the religious opposition to the law something from “the times of the crusades.”

Countries where some regions allow same-sex marriage:

  • Some states in the United States, such as New York, Vermont and New Hampshire, allow gay marriage. Some other states recognise foreign same-sex marriages, while other states including Texas and North Carolina have introduced gay marriage bans in their state constitutions.
  • Mexico City in Mexico has allowed gay marriage since 2010.
  • Gay marriage has been legal in the Brazilian state Alagoas since January this year.

Countries that recognise overseas gay marriages:

  • Israel has recognised same-sex marriages legally performed outside its borders since a Supreme Court ruling in 2006.
  • All Mexican states must recognise gay marriages, even if they don’t choose to perform them, after a Supreme Court ruling in 2010.

World leaders who support gay marriage:

  • US President Barack Obama brought same-sex marriage to the forefront of world debate last week when he said “it is important for me personally to go ahead and affirm that same-sex couples should be able to get married”.
  • Last week Croatian Prime Minister Zoran Milanovic announced that his government is preparing to legalise gay marriage. “I think we must go forward, and be inspired by the most advanced countries in the world. Giving stronger civil legal rights to gay communities will not deprive anyone of their rights,” Milanovic said.
  • Britain’s Prime Minister David Cameron openly supports gay marriage on top of current civil partner laws. “Yes, it’s about equality, but it’s also about something else: commitment. Conservatives believe in the ties that bind us; that society is stronger when we make vows to each other and support each other,” she said in 2011.
  • Incoming President of France, François Hollande, who will be sworn in on Tuesday, has said he will legalise same-s-x marriage while he is in government.
  • New Zealand Prime Minister John Key followed Obama’s lead last week, when he said he is “not personally opposed to gay marriage” in a statement to the Associated Press.

Countries that allow legal civil partnerships (not a complete list):

  • In 1989 Denmark became the first country to allow register partnerships for same-sex couples.
  • Despite proclamations by Germany’s openly gay Foreign Minister Guido Westerwelle that “It’s OK to marry gay,” gay marriage is not yet legal in that country. However, same-sex couples have been able to register civil partnerships in Germany since 2001.
  • Same-sex couples in the UK have similar legal rights to heterosexual couples through its registered partnership laws, which were passed in 2005.
  • Finland, one of the most conservative of the Nordic countries, has had a relationship register since 2002.
  • In 1999 France introduced a civil contract, which gives some rights to gay couples, although this doesn’t include all the rights of marriage.
  • Luxembourg has allowed civil partnerships since 2004.