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".
More top news
One of four men accused of plotting to use a moped in a series of drive-by shootings in London has changed his plea at the Old Bailey.
The North Yorkshire town was divided since the historic bridge was damaged by floods at Christmas.
Syrian President Bashar al-Assad has vowed to regain control of the entire country but warned it could "take a long time".