By Geoff Adams-Spink
Age & disability correspondent, BBC News website
The UN is celebrating the coming into force of the Convention on the Rights of Persons with Disabilities (CRPD) - a landmark agreement that aims to give the world's 650m disabled people full equality.
Adopted in 2006, and opened for signature in March last year it took effect on 3 May a month after the 20th nation ratified it - in this case Ecuador.
This is fast, officials say, reflecting the commitment of some nations to the treaty's goals, as well as pressure from the disability lobby.
The CPRD is the first human rights treaty of the 21st Century
It is estimated that about 10% of the world's population lives with some sort of disability - making disabled people the world's largest minority.
This figure is likely to increase as a result of medical advances and the world's ageing population, according to the World Health Organisation.
Disabled people experience a number of social, cultural and economic barriers which the convention aims to address.
For example, the World Bank estimates that 20% of the poorest people on the planet have a disability.
Disabled women are said to be "multiply disadvantaged" because they experience exclusion on account of their gender and their impairment.
In some countries, disabled child mortality is as high as 80% even when the general level of mortality for the under fives has dropped below 20%.
And almost one in five of less educated people has a disability compared with just over one in 10 of those who are better educated.
The CRPD guarantees disabled people:
- The right to make their own decisions
- The right to say No to being placed in an institution
- The right to say No to medical or psychological treatment
- The right to live in the community
- The removal of barriers to participation in daily life
- Equal opportunities for all
So far some 25 countries have ratified the convention - starting with Jamaica in March last year.
The largest nations that have already ratified it include India, Mexico, the Philippines and South Africa.
Spain, Hungary and Slovenia are the only EU nations on the list so far.
Some countries will ratify the CRPD "with reservations" - in other words opting out of certain sections of it.
For instance, disability campaigners in the UK are critical of their government's "reservations" on residential care, segregating education, employment in the armed forces and freedom of movement for disabled people with regard to nationality and immigration.
"We are seriously concerned that the government appears to be proposing to ratify a watered-down version," said Andy Rickell of pan-disability charity, Scope.
Mr Rickell says the government should not have an "a la carte" approach to the human rights of disabled people.
The British government says that it intends to ratify the CRPD by the end of this year.
"We cannot ratify the convention until we are in a position to ensure that we can fulfil our obligations by implementing the provisions in full," said UK disability minister, Anne McGuire.
"There are still a number of issues that need to be clarified and we cannot ratify it until these have been settled."
The CRPD also has an "Optional Protocol" which provides a means of redress for individuals or groups who feel that their government has violated the convention and where national remedies have been exhausted.
To date, 15 countries have signed the protocol - the UK government says it, too, intends to do so.
For disability rights campaigners, the next step is now clear.
"The global disability community continues to call on all governments to promptly sign, ratify and implement the CRPD and its Optional Protocol without any reservations or declarations," said Lex Grandia of the International Disability Alliance.