BACKGROUND: Research ethics have become universal in their principles through international agreements. The standardization of regulations facilitates the internationalization of research concerning drugs. However, in so-called observational studies (i.e. from data collected retrospectively or prospectively, obtained without any additional therapy or monitoring procedure) the modalities used for applying the main principles vary from one country to another. This situation may entail problems for the conduct of multi-centric international studies, as well as for the publication of results if the authors and editors come from countries governed by different regulations. In particular, several French observational studies were rejected or retracted by US peer-reviewed journals, because their protocols have not been submitted to an Institutional Review Board/Independent Ethics Committee (IRB/IEC). METHODS: National legislation case analysis. RESULTS: In accordance with European regulation, French observational studies from data obtained without any additional therapy or monitoring procedure, do not need the approval of an IRB/IEC. Nevertheless, these studies are neither exempt from scientific opinion nor from ethical and legal authorization. CONCLUSION: We wish to demonstrate through the study of this example that different bodies of law can provide equivalent levels of protection that respect the same ethical principles. Our purpose in writing this article was to encourage public bodies, scientific journals and researchers to gain a better understanding of the various sets of specific national regulations and to speak a common language.