In this paper, we discuss the difficulties in measuring the effectiveness of policies intended to encourage compliance with international carbon restraint agreements. We establish the connection between energy consumption and carbon emissions, and demonstrate a method of disaggregating changes in each into changes in economic activity and structure, energy intensity and fuel mix factors. We utilize this method to analyze the historical trends in energy consumption and carbon emissions in the USA from 1960 to 1993. We analyze the contributions of the various factors to the restraint or encouragement of energy use and carbon emissions. We conclude that, in general, changes in the levels of economic activity have tended, all other factors being equal, to increase emissions, whereas declines in energy intensity and shifts in fuel mix have tended to restrain emissions. Changes in economic structure have had mixed effects. Finally, we discuss the problems with the available data which make the observation of the impact of energy and carbon policies difficult.