In a certain number of countries, such as the USA, a legal action can be brought up by a party aggregating a number of persons (often thousands) which have been affected in a similar manner. This is particularly useful when the damage incurred by each party is too small to make it rational for each party to start such a long and costly process (E.g. consumers over-charged or sold products with defects).

To know more about it, look at what we have already written on this subject