Tenants with one spare bedroom have had a payment reduction of 14% and those deemed to have two or more spare a reduction of 25%.
Lawyers for the 11 cases say that, unless the families move from their homes into smaller properties, they face building up rent arrears and being forced out any way.
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Lorries are being parked on the M20 again as a "heavy volume" of traffic heading for Europe led police to reintroduce emergency closures.
The world's top scientists have called for a ban on autonomous weapons and "killer robots" that can attack targets without human control.
Growth figures published today are set to show the economy bouncing back after a weak start to the year.