Lone parents and their children are going to the UK's highest court in a battle against the Government's controversial benefit cap.
Supreme Court justices will hear several challenges over the lawfulness of the measure in cases brought against the Work and Pensions Secretary.
Part of the proceedings in London, which begin on Tuesday and conclude on Thursday, follow a successful appeal by the Government earlier this year against a High Court judge's ruling that the revised benefit cap unlawfully discriminates against lone parents with children under two.
A panel of seven justices, including the court's president Lady Hale and deputy president Lord Reed, will consider appeals from the families involved in that case.
But they will also hear additional challenges relating to the lawfulness of the curb on all lone parent families - not just those with children under two.
In March, Court of Appeal judges ruled in favour of the Work and Pensions Secretary by a two-to-one majority, overturning a judgment made at the High Court last year by Mr Justice Collins.
The judge, when ruling in favour of lone parents with children under two in their action against the cap, which limits the income households receive in certain benefits, said that "real misery is being caused to no good purpose".
Lawyers for the parents said the reduced benefit cap "drastically reduced housing benefits, leaving lone parent families across the country unable to afford basic life necessities to care for their children".
But, during a hearing at the Court of Appeal in October last year, a QC representing the Government argued that Mr Justice Collins was "wrong and erred in law in determining on the evidence before him that the benefit cap unlawfully discriminated" against the claimants who brought the action.
One of the judges who later allowed the appeal pointed out that "no-one should underestimate the very real hardships caused by the imposition of the cap, and the particular circumstances of the individual claimants in this case bear witness to the harsh circumstances in which they and those similarly placed live".
Also allowing the appeal, Sir Brian Leveson said: "In my judgment it was open to the Secretary of State to take the view that difficulties faced by lone parents with children under two were not such as sufficiently to distinguish that cohort from lone parents with older children, thereby warranting exemption in their case.
"On the contrary, the aims of the policy - whether or not an observer might agree with it - justified treating them in the same way."
The Supreme Court will be asked to rule on whether the revised cap breaches human rights laws, including a prohibition on discrimination.
Challenges against the Court of Appeal's ruling have been brought by three lone parents and two of their children who are under two.
The adults are in receipt of benefits and, as they are not working, are subject to the revised cap.
It is argued on their behalf that they should be exempted because of the particular difficulty for the parent in finding work compatible with his or her childcare responsibilities.
The justices will also hear cases brought by two single mothers and their children, who live outside Greater London, relating to the losses suffered following the January 2017 lowering of the cap on the maximum weekly benefit income from £500 a week to £384.62.
Both women, who have been unable to find work, have children of various ages.
One, with four children, lost entitlement to £80 a week, while a mother of five, who has three children with significant health needs, lost £110.
Polly Neate, chief executive officer at Shelter, said: "This appeal offers a glimmer of hope for the thousands of single-parent families suffering because of the brutal benefit cap."
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