I believe the correct answer is: Deontological ethical
theory.
In moral philosophy, deontology
(or deontological ethnical theory) is an ethical theory which judges the
morality of an action based on whether that action itself is right or wrong
under a set of rules. One of the examples is that killing is wrong even if it’s
self-defense.
Given that he consistently tells
the truth, is fair with my employee, feels a strong moral obligation to make
decisions that do not infringe on the rights of my staff, he is applying the concepts
of deontological ethical theory.