moral obligation(Dubnitsky has thought about leaving many times. "Maybe it sounds pretentious, but I think we have a certain moral obligation to stay," he said.)
in line of duty(Пристав частенько заглядывал к Горбякову, как по нуждам собственного драгоценного здоровья, так и по долгу службы. (Г. Марков, Сибирь) – The police officer frequently called on Gorbyakov, both for purposes of his own precious health and in line of duty. VLZ_58)
