WHEN IRELAND GOES to the polls on 22 May, it could become just the 20th country to entirely legalise same-sex marriage and the first to do so by popular vote.

A further two countries – the USA and Mexico – have legalised same-sex marriage in certain states, but have not federally approved it.

All of these moves came through parliamentary or court decisions, not the ballot box.

Those countries which have legalised same-sex, in chronological order are:

• Netherlands (2000)
• Belgium (2003)
• Canada (2005)
• Spain (2005)
• South Africa (2006)
• Sweden (2009)
• Norway (2009)
• Portugal (2010)
• Iceland (2010)
• Argentina (2010)
• Denmark (2012)
• Uruguay (2013)
• New Zealand (2013)
• France (2013)
• England (2013)
• Wales (2013)
• Brazil (2013)
• Luxembourg (2014)
• Scotland (2014)

In Europe, a number of states, including Ireland, recognise civil unions or other types of partnerships, while the constitutions of Belarus, Bulgaria, Croatia, Hungary, Latvia, Lithuania, Moldova, Montenegro, Poland, Serbia, Slovakia and Ukraine define marriage as a union between a man and a woman, banning same-sex marriage.

In the US, many states have legalised the marriages, but 13 still outright ban them.

They are:

• Arkansas
• Georgia
• Louisiana
• Kentucky
• Michigan
• Missouri
• Mississippi
• Nebraska
• North Dakota
• South Dakota
• Texas
• Ohio
• Tennessee

Colorado allows civil unions, but not same-sex marriage.

In Australia, couples who have been living together for two years reach a de-facto stage in the eyes on the law and are extended a number of legal protections.

Slovenia passed a bill in March that would allow same-sex couples marry and adopt. It is currently awaiting the signature of President Borut Pahor.

Read: We went to the most Catholic county in Ireland to ask about same-sex marriage

Read: Joan Burton says the No posters about surrogacy are ‘sad and demeaning’