What Public procurement refers to the process where governments and public authorities buy goods, works and services from private suppliers. Public procurement law regulates this process, while contracts are the implementation tool for the performance of public procurement goals. The project will provide much needed clarity about the tension between public procurement law and private law - especially contract law. PurpLE will fill a research gap and establish legal tools that support an effective legal framework to facilitate private-public collaboration. Why Current public procurement research is mainly focused on public law. That is the law of a state. Still, private law often impacts the governance of the contract performance and often also disputes resolutions - particularly during the lifetime of large infrastructure projects, e.g. building and managing highway/hospital/school/stadium. Consequently, PurpLE is important from a scientific point of view because it will be the first project to analyse EU sustainable public procurement law against private law concepts that affect procurement goals. How PurpLE's aim will be achieved by investigating three highly complementary research questions: 1) How does public procurement law impact the interpretation of contract law? 2) Can private law limit the outcome of public procurement law and, if so, how? 3) What does this complex interaction between public procurement and private law mean for achieving the United Nations Sustainable Development Goals agenda? SSR Public procurement may be a lever for improving environmental outcomes, driving sustainability change and adding social value. By using purchasing power to choose socially responsible goods and services with lower environmental impacts, public authorities can contribute to achieving the UN Sustainable Development Goals. PurpLE will contribute to the effective realisation of UN Sustainable Development Goals, specifically Goal 12.7 expressly referring to the need for more effective Sustainable Public Procurement implementation.