No one shall be held in slavery and servitude; slavery and the slave trade shall be prohibited in all their forms.
Article 4, Universal Declaration of Human Rights
Usually, they descend into slavery by stages. Ruth Vargas and Luis Colorado certainly did. They were brought to the heart of the Land of Promise wanting to believe things they might only have dreamt about in their native Colombia. "It was all laid out in the contract," says Ruth, her impassive eyes fixed on hands roughened by a lifetime of toil. "Six days work, one day off, English lessons. All here, working for an ambassador in Washington, DC. . . It was our American dream."
Even now, it is hard for Ruth or Luis, or any of the umpteen migrant servants who daily seek solace at the Casa of Maryland employment rights project, fully to comprehend their fate. There was no American dream, much less the hope that gilds it. There was just a long American nightmare, a private hell hidden behind the elegant facade of a townhouse in the shadow of the Capitol.
First came the broken promises. "Luis was hired as the ambassador's chauffeur, but he ended up being the butler, valet and gardener," murmured Ruth, still clearly bewildered.
Then came the rules forbidding them to leave the premises, make telephone calls or talk to strangers; and the heavy workload and docked paychecks. "We were expected to rise at six, but rarely did I ever take off my pinafore before 1 or 2am after serving at lunches, cocktail parties, receptions and dinners," she says.
"There was no time off," snarls Luis, trying to keep his composure. "Our passports were confiscated, and if we complained, we were threatened with deportation."
When, he says, the pair eventually plucked up the courage to ask "the lady of the house" if they could eat together, the answer was a resounding no. "She screamed: 'What are you trying to do, form a union?' That's when we decided to escape."
And so to 734 University Boulevard, and Casa of Maryland. At first, the employment centre looks little different from any of the modest buildings that line the boulevards of Maryland's suburban sprawl - until you glimpse the forlorn figures entering and exiting its swing-doors. For many of Washington's burgeoning army of abused runaway domestics, Casa of Maryland is the first port of call in a clandestine world of safe houses and way stations that some have likened to a modern underground railroad. As its many patrons now testify, the servitude endured by the Colombian couple is not uncommon. Immigration lawyers, human rights groups and NGOs - citing the growing number of lawsuits being filed by the runaways - say the case highlights what goes on in the homes of some of America's prime movers and shakers.
"What is happening to migrant domestics in the Washington area, just a few blocks up from the White House, has reached crisis proportions," says Steven Smitson, Casa's chief attorney. "Unfortunately, the increased focus on immigrants as terrorists has not helped their plight."
"In some cases," said Edward Leary, another immigration lawyer, "there are women who have been kept in basements and not seen the light of day for years."
Around 4,000 domestics - mostly women escaping the rural impoverishment of Asia, Africa and Latin America - are believed to be living in Washington and New York at any one time. Almost all are brought in by staff members of the World Bank, UN and International Monetary Fund (IMF), and by foreign diplomats. Yet while such people see themselves and their jobs as part of the grand mission to eradicate labour abuse and global poverty, all too often it is they who exploit - and sometimes flagrantly degrade, mock and maltreat - those who are less privileged.
"We know of innumerable cases where migrant workers have not only been held against their will, but sexually abused," says Smitson. "And the reason it's so bad is that all these international agencies rely on guest workers who are unaware of their rights, lack any safety net, live in fear of deportation and work in very isolated conditions."
This autumn, Smitson and other activists will step up the campaign for Congress to pass the sort of legislation now needed, at both state and national level, to improve the lot of domestic workers.
In an unprecedented display of solidarity, hundreds of migrant domestics recently demonstrated in support of Ruth and Luis, outside the residence of their former employers. But, like most foreign envoys, the ambassador - a prominent representative of the Organisation of American States - has so far ducked punishment by invoking diplomatic immunity.
It is estimated that in the past decade more than 30,000 domestic workers have entered the US on special visas, sponsored mainly by foreign diplomats and international civil servants. Others are deliberately deceived, the victims of traffickers who have them placed in appalling situations of forced labour. Most migrants follow the example of Ruth and Luis, leaving their own children back home to take up jobs they hope will enable them to feed the families they have left behind.
The US State Department, alarmed by the rise in allegations of abuse, issued a nine-page memorandum outlining its concern that some diplomats abuse their household help. "We stipulated that there were certain requirements that had to be met," Julie Reside, a State Department representative, told me. "And the first was fair and humane treatment."
But while, in theory, no domestic is allowed into the US without a visa based on a written agreement endorsing a minimum wage, social benefits and time off under American law, the contracts are rarely, if ever, monitored.
"The special visa programme, allowing international agencies and embassies to sponsor the workers is at the heart of the problem," says Carol Pier, of the Washington-based Human Rights Watch group. "It leaves migrants very vulnerable to serious abuse. . . Most workers do not speak English and do not know where to go or how to complain. But if they do complain, and they're still with their employers, they risk being fired, losing their legal status and being deported, which scares them more."
Pier, who recently wrote a report on the abuse, discovered that while the servants worked an average 14 hours every day, they earned just $2.14 an hour, far less than the $6.15 minimum wage. Women, who had been lured by employers under false pretences, worked up to 19 hours a day and were paid less than $100 per month.
Not all globe-trotting civil servants treat their staff badly. But as a perk that comes with the job, most bureaucrats prefer to "import" domestics from their own homeland - people who may be of lower caste - not least because their labour comes cheaper than hiring an American worker or even an illegal immigrant.
As Pier also points out, these are people who often live in fear of the reprisals they could suffer back home if they ever went against their powerful masters.
The World Bank, says Edward Leary, has some of the worst offenders. "People there are really bad," he contends. "For 12 years, now, I've been writing World Bank officials foul correspondence, I mean really foul, saying they have to do something about it. I've never got a reply."
Under pressure, the World Bank and IMF agreed, last year, to implement certain internal reforms including the drafting of a code of conduct.
"Every year, I tell these people my door is open, that they can come to me with complaints," says Dick Sullivan, the IMF's first ethics officer. "What I have discovered, when I get the two sides seated here and there," he points to a set of easy chairs, "is that the complaints invariably end up being wage disputes."
But across the board, critics say both agencies are being unrealistic. "Why don't they allow any independent monitoring?" asks Joy Zarembka, head of the Campaign for Domestic Migrant Workers' Rights. "Do they really think most workers will complain to their bosses' boss?"
Earlier this year a Cameroon teenager, who was recently defended by Smitson, heard a US judge sentence a Maryland couple who had enslaved her in their home. The pair were found guilty of forcing the 18-year-old to work as their nanny and housekeeper without any pay for three years. The sentence followed the jailing of another Maryland couple who had "imprisoned" their Brazilian maid, without pay, for 20 years. When she did emerge, shocked neighbours said it was as if the 60-year-old domestic, who had a stomach tumour the size of a football, had come out of the dark.
Recently, Casa of Maryland started a programme which has seen once-abused domestics distribute fliers of support and advice at churches, bus stops and social centres - the sort of places the workers will congregate when they are allowed out.
More and more - perhaps as a result - are emerging from their hidden worlds. But, says Xiomara Salgado, a psychotherapist who counsels abused domestics, "living in a slave-like condition" takes its toll. Even if they do decide to break free, the men and women who have experienced such servitude are unlikely ever to be the same.
"After years of being trapped and isolated, many feel inadequate, powerless and worthless . . . they suffer from nightmares, flashbacks, intense psychological distress, insomnia and hyper-vigilance, and when they do escape, they frequently feel panic-stricken by their new-found freedom."
Ruth Vargas and Luis Colorado would be the first to agree. But they are also determined to let it be known that for some, at least, America is still not the land of the free.
Helena Smith is a foreign correspondent for the Guardian and Observer