I see it not really a fracking issue. Imagine if you could sue the government motor vehicle branch because they issued a licence to a person who killed someone in an accident. Government agencies as the AER exists to implement and regulate the rules set down by the province. If someone does not follow the rules the AER can fine them or make it hard for them to do business or stop them from doing business(similar to getting fined or not being able to renew a drivers licence) but ultimately the company involved must accept responsibility if they are guilty. Imagine what our taxes would be if every government agency that regulates something could get sued......