A slimmed-down US energy bill is on the move through the Senate once more,containing seemingly long-overdue proposals for mandatory rules to ensure powergrid reliability. But how will the rules be enforced? And how will offendingcompanies be penalised?

The issues centre on whether the industry-funded North American Electric ReliabilityCouncil (Nerc) will be given federal backing to enforce reliability standards,as is proposed in the bill. This debate also encapsulates the question of whowill