Prohibition of instrumentalization
According to an ethical theorem first formulated by Immanuel Kant (1785), the complete instrumentalization of people as a violation of their dignity is always ethically prohibited. A complete instrumentalization is present when a person is used solely as a means of realizing purposes (not his own) and is not respected as an end in itself. This idea is not least reflected in Article 1, paragraph 1 of the Basic Law.
Kant, I. (1785): Grundlegung zur Metaphysik der Sitten. Herausgegeben von Karl Vorländer. Hamburg: Meiner, 1994 (Philosophische Bibliothek 41). (German)