Sin of omission, in Catholic teaching, is, as Joseph Delaney states in the Catholic Encyclopedia (1911),the failure to do something one can and ought to do. If this happens advertently and freely a sin is committed. [...] The degree of guilt incurred by an omission is measured like that attaching to sins of commission, by the dignity of the virtue and the magnitude of the precept to which the omission is opposed as well as the amount of deliberation.A person may be guilty of a sin of omission if—as Joseph Delaney states in the Catholic Encyclopedia (1911)—they fail "to do something which [they] are able to do" and which they ought to do, because they have put themself into a state or situation whereby they are unable to complete the action. For example, if a person chooses to drink to excess and is therefore unable to perform a necessary task, that person is responsible for that failure, even though that person is physically unable to perform the task because they knowingly put themself into a state (drunkenness) where accomplishing the task was impossible.
