Applied ethics is the study of existing ethical principles in practical fields of human endeavor, such as medicine, engineering, business, law, and environmentalism. Applied ethics also extends to new moral rules for new situations, such as the rights of airline passengers and disaster victims, moral issues involved in human cloning, and consumer protection. In this sense, applied ethics is practical ethics—it is a study of ethics of practice.

In addition, applied ethics can be more critical as it applies theoretical moral systems and moral theories to practices and fields outside of philosophy. Existing rules and behavior in a given field may be theoretically justified or criticized by philosophical ethicists. In some cases, new moral directions may emerge. Environmental ethics is a good example of the theoretical dimension of applied ethics.