Most engineering codes of ethics worldwide exhort engineers to consciously put the public interest above all others. This seems to run counter to the market philosophy that the public interest will be achieved by individuals pursuing their own self-interest. It is this latter philosophy that is at the heart of sustainable development with its emphasis on economic valuation and economic instruments to achieve environmental protection. Sustainable development policies generally embody an economic determinism with respect to technological change. These policies avoid the issue of ethics and assume environmental and economic goals are compatible. Yet engineers today are grappling with the ethical dilemmas posed by everyday conflicts between the economic and environmental requirements of their work. In the past conflict between self-interest and public interest was seldom a problem for engineers, since engineering works were almost synonymous with human progress. Today environmental issues have created a divergence between self-interest, employer interest, professional interest and public interest. But how realistic is it to expect engineers to display higher ethical standards than those normally expected of the wider community? And can individual ethics play a significant role in influencing technologies that are collectively shaped by professional paradigms and philosophies?