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

The document examines the Most-Favoured-Nation (MFN) clause in investment treaties, focusing on the legal uncertainty created by divergent interpretations from arbitral tribunals. It specifically analyzes the controversy surrounding the 'importation' of substantive and procedural rules from third-party treaties, the distinction between pre- and post-establishment treatment, and the risk of 'treaty shopping.' The guide concludes with strategic recommendations for states to protect their sovereignty and regulatory space by refining the drafting of MFN clauses or omitting them entirely in future treaties.

• The MFN clause is a conventional obligation and 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.
• Since the Maffezini v. Spain case in 2000, some arbitral tribunals have allowed investors to use MFN clauses to import more favorable dispute settlement procedures from third-party treaties, such as bypassing the requirement to first exhaust local courts.
• Tribunals are generally open to using MFN clauses to import substantive protections that are missing or more restrictive in the base treaty, such as Fair and Equitable Treatment (FET) standards or more favorable compensation criteria for expropriation.
• Most tribunals reject the use of MFN clauses to expand the scope of a treaty ratione temporis (retroactively) or ratione materiae (such as altering the definition of 'investment').
• There is a significant split in jurisprudence regarding procedural rules: while some follow the Maffezini approach, others argue that MFN clauses do not apply to dispute settlement unless explicitly stated, as states likely never intended such an application when drafting older treaties.
• The 'selective importation' of treaty provisions—where an investor takes a benefit from a third-party treaty but ignores its accompanying limitations (like an irrevocable option clause)—has been accepted by some tribunals but rejected by others as 'artificial' cherry-picking.
• Extending MFN treatment to the pre-establishment phase (admission, acquisition, and expansion) significantly limits state sovereignty, particularly for developing countries, as it restricts the ability to maintain discriminatory entry conditions.
• To mitigate risks, states are increasingly adopting specific drafting strategies: excluding dispute settlement mechanisms from MFN scope, excluding all treaties signed before a certain date, or omitting the MFN clause entirely.

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} }