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.
Lawyers in 10 cases at London's High Court are seeking a ruling that the regulations, introduced on 1st April, "unjustifiably discriminate against housing benefit claimants who are disabled or care for disabled family members".
Outside court protesters gathered in support of the families.
More top news
An ex-boyfriend murdered a couple after he searched on google for videos on getting revenge and the lengths of sentence for murder.
The man was taken to hospital after the car he was travelling in was hit by a tree.
After the awards were overshadowed by an extraordinary error over the best film, ITV News breaks down exactly what went wrong.