The fact that countries like China and India use more coal is not because they prefer it, but because of their abundant supplies of coal and its relatively lower price compared with its more environmentally friendly substitutes. Thus, while some countries or regional agreements (e.g. North American Free Trade Agreement) may have a negative list on services or on investments in certain technologies which are restricted, it is most unlikely that countries will broadly agree on a list of goods that need to be banned. Moreover, arguably, for the purpose of meeting a climate change mitigation objective, any likely ban or restriction would tend to be on goods that emit high levels of GFIGs. This will face resistance from countries that object to the use of trade restrictions based on process and production methods (PPMs), partly because it is difficult for customs officials to distinguish between high and low GHG-emitting products.