This paper examines the principle of Respect des fonds, its history and reason for becoming a dominant principle, and what its aspects mean: interpreting original order as an internal arrangement, and discussing external arrangement in the principle of provenance. Case studies (both real world examples and hypothetical examples based on real fonds and archives) will be used to discuss how the twin principles of respect des fonds, original order and provenance can be put into practice. The case studies are used to discuss what problems can arise in the application of respect des fonds.