Our last excursion into custom will be the custom of duty.
In example, a single person, with no duty for the protection of others, may legitimately choose to suffer death rather than defend life. Those having a duty to defend the life of others—
police officers, parents—must use force, even deadly force to defend the life of others.
This situation is complex. A mother may go to the lions of the Roman arena with her infant child, but not necessarily with her child who has attained the age of reason (seven years), who does not wish to go.
A civic official must provide a police force for the safety of the public, this is his duty. This same civic official may opt not to resist an attack on his own life, out of moral or religious convictions.