ENGOs perspectives on emissions trading are increasingly dependent on the details of individual emissions trading programs and judgments of whether a program's particular environmental pros and cons outweigh the pros and cons of "command and control" alternatives. On the "pro" side of the emissions trading ledger, trading may help reduce costs of achieving a particular goal. This may, in turn, make more stringent environmental pollution goals more politically achievable, or may allow agencies to shift their attention to other problems. On the "con" side of the emissions trading ledger, there are many aspects of trading programs that need to be assessed. In particular, environmentalists are likely to pay particular attention to the following:
• the monitoring and enforcement regime under a trading program must be sufficiently strong to withstand new opportunities and incentives for non-compliance created by a trading program;
• a trading program must be accompanied by regulatory and planning changes which will help to ensure the correction of "market failures";
• the political difficulties in developing an emission allowance trading program, in particular, the politically sensitive issue of allowance allocation, may lead to a situation where real emission reductions are delayed;
• poorly designed trading programs may not safeguard environmentally sensitive areas or particular communities.