A newly introduced law allows British courts to hear US-style class actions - where one or several people sue on behalf of a much larger group.
The Consumer Rights Act 2015 will make it far easier for groups of consumers to seek compensation from firms that have fixed prices and formed cartels.
It introduces "opt out" actions where everyone affected is automatically a member of the "class" which is suing.
Consumer groups say it is a huge step forward in helping secure compensation.