In Ontario, the Court of Appeal has affirmed earlier rulings that gamblers who self-excluded, but who were not effectively kept away from continued casino gambling, can not pursue a class action lawsuit against the casino operators, the Ontario Lottery and Gaming Corporation. The court upheld the trial judge's reasoning that potential liability was dependent on personal circumstances, so that the members of the would-be class were not sufficiently similarly situated to justify class certification. Individual lawsuits can still proceed, of course, and many in the past have led to substantial settlements.
Self-Exclusion noted the trial court ruling back in 2010, followed last year by the Court of Appeal's announcement of its willingness to hear the appeal. Here's a short video (with links to two more videos) on self-exclusion provided by the Ontario Lottery and Gaming Corporation.