Due to public concern over the environmental impacts of plastic shopping bags many countries, states, towns and councils are implementing measures to address their use.While a number of individual retailers in New Zealand have taken steps to reduce plastic bag consumption, there has been limited national or regional government action to address plastic shopping bag use. While other countries have favoured economic instruments, such as Ireland's "PlasTax", under a cost benefit analysis research has identified that all policy interventions are cost inefficient.1
This thesis uses a mixed comparative approach to investigate the environmental impacts of plastic shopping bags and consumption patterns, in relation to international practice, alternatives to plastic shopping bag, and policy options.
The mixed comparative approach used in this research is a combination of the philosophies underlying cost benefit analysis, sustainable development, triple bottom line reporting, case studies and policy analysis. Voluntary actions are
identified as the least costly option, but achieve smaller reductions in plastic shopping bag use. In contrast regulatory actions are more likely to achieve greater reductions in plastic bag use, but are costly and have less public and political 
acceptance. Economic instruments while achieving modest to high reductions in plastic shopping bag use, are moderately costly, and also face acceptance and implementation constraints. However, due to strong public pressure for government intervention, and potential implications for future climate change and sustainability initiatives, it is suggested that economic instruments and regulatory options are the most likely choices for government policies to address plastic shopping bags