Tomkins and Twomey 1994 offer an outline and discussion of the use of a marketable permit system (MPS) approach to address international pollution problems. Whilst the economic principles underpinning the use of MPSs is not disputed, it is argued that the nature of their associated discussion is misleading. It is suggested that they significantly underplay a variety of problems impacting on the negotiation, costs and practical application of the approach. In addition, the various incidental comparisons with the use of “command and control”, and fiscal instruments therein, seem to imply general superiority of the MPS approach over these approaches to address internationalpollution problems. It is argued that this is not likely to be the case.