The are many ethical issues that may prevent the project going forward, including, but not limited to:
- The project benefits from the hardship of others
- The project negatively affects the surrounding natural environment
- The project's budget takes into consideration cheap/underage labor
- The stakeholders need to bribe someone in order to secure the contract for the project.
I think that there are many other ethical reasons for a project not to be executed, but the above are the main ones!