A second formulation of the imperative, often used in health care, requires that we never treat another person solely as a means to our end. For example, involving people in a risky medical experiment without their knowledge deprives them of their ability to make a rational choice about participation and uses them as a means to some other end. The fact that the knowledge gained from the research might benefit thousands of other people is not relevant in this perspective.

Kant recognizes two general categories of duties. A perfect duty is one we must always observe, such as our duty not to needlessly harm another person. Other duties, such as acting with benevolence, are not required in all circumstances, so they are termed imperfect duties.

The primary strengths of Kantian ethics in the health care context are that it prohibits us from using oneself or others solely as means to another end and requires us to be consistent in our moral action. For example, we should not experiment on people solely for the benefit of others; and, if it were wrong to involve one set of subjects in dangerous research without their consent, then it would be wrong to involve any subject in dangerous research without their consent. Some of the weaknesses of a strict Kantian perspective are the absence of any guidelines for dealing with the inevitable conflicts between duties and the lack of recognition that emotion and intuition can play a constructive role in ethical decisions. For example, an absolute duty to tell a patient the truth might cause a patient harm in certain circumstances; therefore the duty to always tell the truth conflicts with the duty to avoid needless harm or injury. Furthermore, human emotion and intuition can be helpful in detecting the potential for harm, and it is probably not realistic or even desirable to completely eliminate these natural abilities from our moral actions.