The aim of this research is to develop and propose a framework to supplement existing government frameworks for the selection and prioritisation of large public capital projects. The effectiveness of the existing Australian frameworks are tested against three large public projects. Case study analysis indicated Optimism Bias and Focalism were cognitive traits that influenced key decision-making along with legislature structures. The result of the analysis showed the proposed framework is capable of mitigating risks of improper project selection through criterion analysis of quantitative and qualitative measures, however empirical analysis is required to further test assumptions.