Disabled adults and families with disabled children are challenging the legality of the Government's so-called "bedroom tax", arguing that it unlawfully discriminates against them.
New housing benefit regulations have led to reductions in benefit payments to tenants in the social housing sector assessed to be under-occupying their accommodation.
Lawyers in 10 cases at London's High Court are seeking a ruling that the regulations, introduced on April 1, "unjustifiably discriminate against housing benefit claimants who are disabled or care for disabled family members".
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UK defence secretary says so-called Islamic State group will only be defeated by force.