The chief difficulty with formal applied ethics is that many persons can disagree with the selected starting ethical theory. For example, it is known that both Christians and Muslims often disagree with utilitarian solutions - their ethics involve reference to a pre-existing moral code for divine sources. This introduces case prototypes and precedents which are not universally acceptable to all participants.
To avoid this problem, one of the newer approaches to applied ethics is to revive the ancient practice of casuistry. Casuistry attempts to establish a plan of action to respond to particular facts - a form of case-based reasoning. By doing so in advance of actual investigation of the facts, it can reduce influence of interest groups. By focusing on action and not the rationale, it can reduce influence of prior bodies of precedent and explicit moral codes.
In a modern casuistic approach to say, a biomedical issue, two boards of experts are appointed. The ethical board might represent disparate ethical theories, e.g. a Jew, Christian, Buddhist, Humanist and Muslim. The scientific board represents relevant medical, legal, psychological and philosophical disciplines. The ethical board evaluates situations, and recommends and ratifies responses. The scientific board explains the causes and effects of each ethical state and response.
The boards then consider actions that are appropriate for relevant pure cases. For example, most ethical systems agree that assault deserves punishment, while risking oneself to save lives deserves reward. Other cases that are often relevant include theft, gifts, verified truth, verified lying, betrayal, and earned trust.
Taking such cases as data, the board draws parallels with the problem under consideration, and attempts to discover a set of actions to respond to the case under consideration.
For example, medical experiments without informed consent, performed on healthy persons, are often likened to assault with a deadly weapon performed by the experimenter. The experiments usually involve equipment or drugs, which provides the 'weapon.' The experimenter's malice is indicated by the secrecy. Therefore, harmful results can be attributed to the malice, and the degree of damage indicates the degree of assault.
If the experimenter gets informed consent from the subject, the scenario transforms completely because the moral choice moves from the experimenter to the subject. With informed consent, the subject then becomes either a tragic hero if the procedure fails, or a successful hero if the procedure succeeds. The experimenter is then merely offering a brave volunteer an opportunity to contribute to human knowledge, and possibly benefit from the process.
Note that in both cases, "villain & victim," or "scientist & volunteer," the actual experiment might cause the same clinical results. However, the moral relationships of the participants are completely different.
Since casuistry is concerned with facts and actions, rather than theories, it is often remarkably easier to come to agreement. Although many ethical systems disagree about the justification for an action, the actions that they recommend are often remarkably similar. There can be many rationales for the same action, thus avoiding any single rationale or the necessity to agree on language seems to remove a major barrier to agreement. In legal terms, it removes the fear of setting precedent.
Such an action-focused approach to applied ethics is thus also less likely to conflict with informal ethical theories of politics, etiquette, aesthetics and arbitration - each of which implies their own concept of a valid precedent. In fact an approach based on casuistry involves practices from all of these - especially the production of hypothetical cases for deriving a common ethic - but does not permit the arbitrary introduction of precedents from any of them.
A specialized example of casuistry is a science court[?], in which scientists agree in advance what scientific theory would best explain a set of facts and thus what research program is recommended - making it extraordinarily difficult for scientists to disagree with that action if those facts turn out to be true. A similar approach can be taken to engineering and regulatory decisions, with advocates of different potential actions competing to establish themselves. These applications to public policy tend to resemble that of more traditional politics.