La clause de la nation la plus favorisée dans les traités d’investissement

This guide by the International Institute for Sustainable Development (IISD) analyzes the Most-Favoured-Nation (MFN) clause in investment treaties, focusing on how divergent interpretations by arbitral tribunals have created legal uncertainty. It examines the distinction between substantive and procedural rules, the risks of 'treaty shopping,' and provides recommendations for states to limit the scope of MFN clauses in new and existing treaties to protect national sovereignty and policy space.

• The MFN clause is a conventional obligation, not a rule of customary international law, meaning a state is only bound by it if it has explicitly committed to it in a treaty.
• Arbitral tribunals have diverged on whether the MFN clause can be used to import procedural rules from third-party treaties, such as bypassing requirements to exhaust local remedies before seeking international arbitration.
• Jurisprudence generally supports using the MFN clause to replace a treaty provision with a less restrictive one or to import a protection rule that is entirely absent from the base treaty.
• Most tribunals oppose using the MFN clause to extend the scope of a treaty, such as attempting to apply a treaty retroactively (ratione temporis) or expanding the definition of 'investment' (ratione materiae).
• The 'Maffezini' interpretation allows investors to potentially create a 'super treaty' by selectively picking favorable provisions from various treaties, which the document describes as 'treaty shopping.'
• There is a distinction between post-establishment MFN treatment (the majority approach) and pre-establishment treatment (a growing minority approach). Pre-establishment MFN grants rights regarding the admission, acquisition, and expansion of investments, which significantly limits state sovereignty.
• To mitigate risks, states are increasingly adopting specific exclusions in new treaties, such as explicitly removing dispute settlement mechanisms from the scope of the MFN clause or excluding all treaties signed before a certain date.
• Some states and regional models, such as the 2012 SADC model and the 2015 Indian model, have moved toward the radical option of not including an MFN clause at all in their investment treaties.

APA

Nikièma, S. H. (2017). La clause de la nation la plus favorisée dans les traités d’investissement. International Institute for Sustainable Development. https://www.iisd.org/system/files/publications/mfn-most-favoured-nation-clause-best-practices-fr.pdf

Chicago

Nikièma, Suzy H. La clause de la nation la plus favorisée dans les traités d’investissement. International Institute for Sustainable Development, 2017. https://www.iisd.org/system/files/publications/mfn-most-favoured-nation-clause-best-practices-fr.pdf.

Wikipedia

{{cite report |last1=Nikièma |first1=Suzy H. |title=La clause de la nation la plus favorisée dans les traités d’investissement |publisher=International Institute for Sustainable Development |date=February 2017 |url=https://www.iisd.org/system/files/publications/mfn-most-favoured-nation-clause-best-practices-fr.pdf |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{nikima2017clause, author = {Nikièma, Suzy H.}, title = {{La clause de la nation la plus favorisée dans les traités d’investissement}}, institution = {International Institute for Sustainable Development}, year = {2017}, month = feb, url = {https://www.iisd.org/system/files/publications/mfn-most-favoured-nation-clause-best-practices-fr.pdf}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }