Principlism: bioethics as procedure?

In their book Principles of Biomedical Ethics, Tom Beauchamp and James Childress offer an account of bioethics, called “Principlism”, by way of specifying and balancing four clusters of principles.2 These principles are found, as the author state, in a common morality, understood as a set of universally shared moral beliefs. This paper seeks to introduce the following questions: Does this account of Beauchamp and Childress flow from common morality in a natural way? Can their proposals claim to be endorsed by the authority of common morality? If not, in what way does Principlism contribute to bioethics