The proposed Emissions Trading Scheme (ETS) relies on regulations, not on law.
It's the same as circumstance surrounded the failed Australia Card in 1987.
Hawke went to a double dissolution election using the senate obstruction of the card as a trigger. Although Labor won the election and was busy setting up a joint sitting of parliament, the tee wee matter of the start-up date for the card blew everything out of the water. The start date was governed by regulation - not law - a regulation that the senate could and would have voted down.
Outcome: ID card abandoned.
The Clerk of the Senate, and the shadow attorney-general are both of the opinion that the same legal defect surrounds the ETS.
It would seem the script Rudd and everyone else had in mind for the next six months or so will undergo on-the-run re-writes. It's not going to play to plan after all.