Canada never ceases to think of the WTO as the last resort for defending some of the worst aspects of its public policies. Usually, Europeans are the target. There was asbestos, then more recently, seals and now they are rattling the WTO sabres about the oilsands. The EU is considering giving petroleum products from the oilsands a relatively "dirty" rating, based on studies about the life-cycle contributions to emissions from these fuels. A letter from Canadian EU Ambassador Plunkett to Connie Hedegaard, the European climate czar, was just brought to public view, thanks to Friends of the Earth Europe. As you can see it contains oh-so-threatening language about the WTO: http://www.cbc.ca/news/world/story/2012/02/20/oil-sands-crude-eu.html.
As long as the EU's regulatory process hasn't been somehow highjacked by anti-Canadianism, or other illegitimate interests, and follows due process of law, the WTO dispute settlement organs are not going to be in the business of replacing the EU's scientific judgments with those of Canada's own experts. In Brazil-Tyres, which doesn'tdirectly address climate issues, the Appellate Body went out of its way to mention climate change as an example of a regulatory challenge where a considerable margin of appreciation would be afforded to a Member as to what would be required to justify its measure under Article XX of the GATT (paragraph 151). Even under SPS, which has certain requirements of scientific justification that wouldn't apply here since the tar sands is not an SPS matter, in EC-Hormones Suspension the AB made it clear that the role of the WTO dispute settlement organs is not to engage in de novo review of the scientific and regulatory judgments of WTO Members, substituting their own view of scientific methodology and evidence for that of the regulating Member.
Canada's fast and loose use of WTO litigation as a threat raises issues under the DSU. Consider Article 3.10: "It is understood that requests for conciliation and the use of the dispute settlement
procedures should not be intended or considered as contentious acts and that, if a dispute arises,
all Members will engage in these procedures in good faith in an effort to resolve the dispute."
In the case of EU-Seals Canada filed its challenge with great bluster, probably more interested in threatening not the EU itself but Russia or Asian countires where the fate of its seal industry may ultimately be decided-obviously with Russia that hasn't worked. But at the same time Canada may well now be stalling the composition of the panel in Seals (either directly or indirectly). As 3.10 suggests, WTO complaints should not be used as a hanging threat-either Canada should withdraw its complaint or support an expeditious panel process.