Lone mothers have narrowly lost their Supreme Court challenge to cutbacks in the benefits system.
The highest court in the land has ruled by a 3-2 majority verdict that the Benefit Cap (Housing Benefit) Regulations 2012 are not unlawful.
The decision was a blow for two women forced after suffering domestic violence into temporary accommodation in London who brought the legal challenge.
Their lawyers argued that the cuts violated human rights laws and had a disproportionate and discriminatory effect on women, especially those seeking to escape violent partners.
The Supreme Court decision upholds a Court of Appeal ruling that the capping measures were lawful.
The benefit cap limits the amount of benefits a household can receive to £500 a week for couples and £350 a week for households of a single adult.
Work and Pensions Secretary Iain Duncan Smith said: "I am delighted that the country's highest court has agreed with this Government and overwhelming public opinion that the benefit cap is right and fair.
"I am proud to say that it is one of the most significant reforms we've implemented over the past five years.
"A key part of the long-term economic plan, the benefit cap is encouraging people to change their behaviour and motivating them to find work."
The two lone parents went to the Supreme Court, along with a representative child from each family.
Their lawyers argued that the cap unjustifiably discriminated against abuse victims, who are predominantly women, and failed to have regard to the best interests of the child.
They said the cap substantially reduces weekly income and puts the mothers at risk of losing their safe homes.
The justices hearing the case included Supreme Court deputy president Lady Hale, Lord Kerr, Lord Reed, Lord Carnwath and Lord Hughes.
Lord Reed, giving the lead judgment, said he accepted that the cap was "a proportionate means" of meeting legitimate Government aims, which include deficit reduction and incentivising parents to find work.
He noted that the cap for households with children was equivalent to a gross annual salary of £35,000, which is higher than the earnings of half of the UK's working households.
Although the short-term savings were a small proportion of the total welfare budget, they nevertheless contributed towards deficit reduction, and were also intended to change behaviour over the longer term.
But Lady Hale - one of the dissenting judges - ruled that the Government had failed to take proper account of "the best interests of the children", as it was obliged to do under the UN Convention on the Rights of the Child (UNCRC).
Lady Hale said UNCRC was relevant even though it was not yet generally part of domestic law.
She ruled that the cap deprived some children of provision for their basic needs, which could not be in their best interests.
The cap's aim of incentivising parents to seek work discriminated against lone parents as they were the least able to do so, said Lady Hale.
The Child Poverty Action Group (CPAG) said that, although a majority of the justices upheld the cap as lawful, a majority also criticised it for breaching the UNCRC.
The charity said the Supreme Court left the cap intact because the UNCRC, which requires the interests of children to be paramount, was not incorporated into domestic law.
But the court decision puts pressure on the Government to reconsider its compliance with international law.
The CPAG highlighted the pivotal judgment of Lord Carnwath, who dismissed the appeal but expressed the hope that the Government would address breaches of children's rights in a review of the cap.
CPAG chief executive Alison Garnham said: "The women and children involved in this case were escaping horrific abuse.
"As three of the judges have said, 'It cannot be in the best interests of the children affected by the cap to deprive them of the means of having adequate food, clothing, warmth and housing'.
"We hope the Government will listen to the court and comply with international law on the protection of children."
Children's charity Barnardo's expressed disappointment with the court's decision and called on the Government to help vulnerable children fleeing abuse with their mothers.
Alison Worsley, deputy director of strategy, said: "W e are disappointed at the court's decision today which will make it harder for families to escape from domestic violence.
"Every day we see the human cost of housing benefit changes - cuts to the emergency 'social fund' hardship grant scheme forced a family fleeing domestic violence to sleep on concrete floors when they were rehoused because beds weren't available and they couldn't afford carpets.
"The Government must now put in place measures to ensure that vulnerable children and young people fleeing abuse and intolerable situations are not left without a roof over their heads."