Thanks to today's decision by the US Supreme Court, and a much quieter decision by the Supreme Court of Mexico two weeks ago, there are now a billion people living with marriage equality. Progressives have won this issue with an unbelievable speed. 15 years ago it was illegal to have a same-sex marriage anywhere in the world. Netherlands broke the taboo in 2001, followed by Belgium (2003), Spain, Canada (2005) and South Africa (2006). Conservatives crowed with the first major setback in 2008 (when California legalised and then criminalised same-sex marriages), but since then victory has been accelerating, with a stampede across Europe and South America. Today we just crossed the one billion mark for people living in countries with same-sex marriage.