I will present the practicalities related to the care and display of Homogen Infiltration für Kontzertflügel (Joseph Beuys, 1966) between 1976, the acquisition of the work of art by The Musée National d’Art Moderne (MNAM) and 1992. The acquisition coincided with the inauguration of the Centre Georges Pompidou. Its ambitious mission was to democratize access to culture, to promote contemporary art and to create a museum, which would enable Paris to regain a leadership position in the art world. First, I will describe the evolution of how the artwork has been categorized. Originating from a “Fluxus action” in which Beuys performed, it then became a stand-alone work which was acquired from the artist. Following acquisition, several conservation treatments were then performed before a major intervention, performed by the artist in 1984, transformed the stand-alone work to an element of an Installation. The artist died soon after installing it in the MNAM gallery. Finally, in 1992, the Installation was dismantled and the artwork returned to a stand-alone work status. I will describe the ways in which the implication of integrity and authenticity changed as the work of art was successively re-categorized. Then, I will present the theoretical limitations of the ethical principles of conservation that emerged from such evolution. Contrasting the actual practical choices applied in the successive conservation treatments with the ethical conservation principles reveals different conflicting phases within the MNAM conservation department attitude towards authorship. The decision-making of the earlier phase can be considered as pioneering with regards to actual ethical debates concerning the conservation of artworks resulting from what it is now defined as Experimental genre. The limits of the ethical principles were overcome in an innovative way thanks to a flexible attitude adjusting the decisions to the MNAM mission statement and collaborating with the artist. However, a later conservation treatment, performed without informing the artist, resulted in a major conflict between Beuys and the institution. It also indicates an implicit change in the attitude of the conservation department. This conflict was “resolved” by the conservation treatment that the artist carried out in 1984. Though this treatment is often presented as an exemplary collaboration between artist and institution, I will show that its results and process contradict what can be considered as an ethical conservation treatment. Complementing the documentation provided by the conservation files with a detailed study of the practicalities surrounding the designation and exhibition of the artwork at the MNAM further demonstrates the existence of an implicit register of decision making. This register strongly informed the museum agency on the authorship of the work of art. Indeed, more than temporarily framing the production of meanings, the museum agency irreversibly transformed the nature of the work of art in 1992. This register of practical decision making did not correspond to either of the two narratives produced by the institutional mission statement and the prevailing conservation deontology. However, contextualizing it in the history of the MNAM shows that its emergence resulted from both the contextual agenda of the Centre Georges Pompidou and different attitudes of a succession of prominent MNAM staff towards the inherent tension within its original mission statement.