THE HARMONIZED DISSONANCE OF TRADE USAGES: TURKISH LAW VS. LEX MERCATORIA

10.51204/Anali_PFBU_26202A

The Turkish Commercial Code distinguishes between commercial customary law and trade usage. Trade usage may be defined as actual practices or habits used in the interpretation of declarations of will in commercial relations, but which have not attained the status of customary law, unless the legislator has expressly provided for their application. In judicial decisions, however, trade usage is often treated as an abstract principle of law rather than as a concrete habit or practice to be applied in a particular dispute. After examining whether trade usages may serve as a basis for judicial decisions under Turkish law, this paper highlights the erroneous approach to trade usage in Turkish case law. It then compares Turkish law with relevant international instruments and examines whether the case law of the Turkish Court of Cassation is compatible with international commercial regulations.

1. ] Acar, Hakan, Ahmet Cemil Yıldırım. 2008. The New Draft for the Turkish Code of Obligations: The Comparative Study with The UNIDROIT Principles of International Commercial Contracts. Journal of Qafqaz University 24: 10–29.
2. Arkan, Sabih. 2025. Ticari İşletme Hukuku [Commercial enterprise law]. Ankara: BTHAE.
3. Ayoğlu, Tolga. 2011. Uluslararası Ticari Sözleşmelere Uygulanan Genel Prensipler, Maddi Hükümler ve Ticari Adet-Teamüller Olarak Lex Mercatoria [Lex mercatoria as general principles, material provisions and commercial customs applicable to international commercial contracts]. İstanbul: Vedat Kitapçılık.
4. Bingöl, Fatma Itır. 2017. Lex Mercatoria ve Türk Tahkim Hukuku’ndaki Yeri [Lex mercatoria and its place in turkish arbitration law]. Dokuz Eylül Üniversitesi Hukuk Fakültesi Dergisi 19: 1953–1969.
5. Bonell, Michael Joachim. 1/1996. The UNIDROIT Principles of International Commercial Contracts and CISG-Alternatives or Complementary Instruments? Uniform Law Review 1: 26–39.
6. Coetzee, Juana. 2–3/2015. The Role and Function of Trade Usage in Modern International Sales Law. Uniform Law Review 20: 243–270.
7. Dimatteo, Larry A., Janssen, André. 2014. Interpretive Methodologies in the Interpretation of the CISG. 79–101 in International Sales Law A Global Challenge, edited by Larry A. Dimatteo. Cambridge: Cambridge University Press.
8. Edis, Seyfullah. 1997. Medeni Hukuka Giriş ve Başlangıç Hükümleri [Introduction to civil law and preliminary provisions]. Ankara: Ankara University.
9. Ferrari, Franco. 2003. Trade Usage and Practices Established between the Parties under the CISG. International Business Law Journal 5: 571–580.
10. Gélinas, Fabien. 2015. Toward a Transnational Law of Trade Usages? Y.B. Arb. & Mediation 7: 49–57.
11. Güven, Koray. 2/2014. Lex Mercatoria ve Milletlerarası Tahkim [Lex Mercatoria and international arbitration]. Public and Private International Law Bulletin 34: 1–57.
12. Işıktaç, Yasemin. (1992). Hukukun Kaynağı Olarak Örf ve Âdet Hukuku [Customary law as a source of law]. İstanbul: Kazancı Hukuk Yayınları.
13. Kaplan, İbrahim. 1987. Hâkimin Sözleşmeye Müdahalesi [Intervention of the judge in the contract]. Ankara: Kadıoğlu Matbaası.
14. Lando, Ole. 4/1985. The Lex Mercatoria in International Commercial Arbitration. The Lex Mercatoria in International Commercial Arbitration 34: 747–768.
15. Lookofsky, Joseph. 2022. Understanding the CISG A Compact Guide to the 1980 United Nations Convention on Contracts for the International Sale of Goods. Alphen aan den Rijn: Kluwer Law International B.V.
16. Levie, Joseph H. 6/1965. Trade Usage and Custom under the Common Law and The Uniform Commercial Code. New York University Law Review 40: 1101–1117.
17. Mak, Vanessa. 2016. Art. 67: Contract Interpretation and the Role of ‘Trade Usage’ in a Common European Sales Law. 115–132 in Contents and Effects of Contracts – Lessons to Learn From The Common European Sales Law, edited by Aurelia Colombi Ciacchi. London: Springer Internatinoal.
18. Oğuz, Arzu. 3/2001. Hukuk Tarihi ve Karşılaştırmalı Hukuk Açısından Uluslararası Ticaret Hukuku: Unidroit İlkelerinin Lex Mercatoria Niteliği [International trade law from the perspectives of legal history and comparative law: The nature of the UNIDROIT Principles as lex mercatoria]. Ankara Üniversitesi Hukuk Fakültesi Dergisi 50: 11–53.
19. Özkan, Işıl. 2021. Yeni Lex Mercatoria ve Kaynakları [New lex mercatoria and its sources]. İstanbul: Oniki Levha.
20. Pamboukis, Charalambos. 1/2005. The Concept and Function of Usages in the United Nations Convention on the International Sale of Goods. Journal of Law and Commerce 25: 107–131.
21. Polanski, Paul P., Robert B. Johnston. 2/2002. Potential of Custom in Overcoming Legal Uncertainty in Global Electronic Commerce. The Journal of Information Technology Theory and Application 4: 1–16.
22. Poroy, Reha, Hamdi Yasaman. 2024. Ticari İşletme Hukuku [Commercial enterprise law]. Ankara: Seçkin.
23. Schmidt-Kessel, Martin. 2022. Article 9 CISG: Usages and Practices. 200–217 in Commentary on the UN Convention on the International Sale of Goods (CISG), edited by Ingeborg Schwenzer and Ulrich G. Schroeter. Oxford: Oxford University Press.
24. Schmitthoff, Clive M. 1961. International Business Law: A New Law Merchant. 129–153 in Current Law and Social Problems Vol. 2, edited by Ronald St. John Macdonald. Toronto: University of Toronto Press.
25. Schmitthoff, Clive M. 1964. The Law of International Trade, Its Growth Formulation and Operation. 3–38 in The Sources of the Law of International Trade, edited by Clive M. Schmitthoff. London: Stevens.
26. Schmitthoff, Clive M. 1988. Nature and Evolution of the Transnational Law of Commercial Transactions. 231–242 in Clive Schmitthoff’s Selected Essay’s on International Trade Law, edited by Chia-Jui Cheng. London: Brill.
27. Serozan, Rona. 2015. Medeni Hukuk, Genel Bölüm, Kişiler Hukuku [Civil law, general section, law of persons]. İstanbul: Vedat Kitapçılık.
28. Smythe, Donald J. 1/2016. Reasonable Standards for Contract Interpretations under the CISG. Cardozo Journal of International and Comparative Law 25: 1–28.
29. Tanverdi, S. Mücahit. 1991. Medeni Usul Hukuku’nda Bilirkişilik [Expert indication in civil procedure law]. İstanbul: İstanbul University.
30. Tekinalp, Ünal. 2022. Ticarî Teamül Üzerine Değerlendirmeler [Evaluations on trade usage]. 625–638 in Prof. Dr. Zühtü Aytaç’a Armağan [Festschrift for Prof. Dr. Zühtü Aytaç]. İstanbul: Oniki Levha.
31. Ulusoy, Erol. 2001. Türkiye’de Geçerli Olan Ticari Öf, Adet ve Teamüller, Fire ve Zayiat Kararları [Commercial customs and trade usages valid in Türkiye, loss and damage decisions]. İstanbul: Türkmen Kitabevi.
32. Umar, Bilge, Ejder Yılmaz. 1980. İsbat Yükü [Burden of proof]. İstanbul: Kazancı Matbaacılık.
33. Ülgen, Hüseyin, Mehmet Helvacı, Abuzer Kendigelen, Arslan Kaya, N. Füsun Nomer Ertan. 2019. Ticari İşletme Hukuku [Commercial enterprise law]. İstanbul: Vedat Kitapçılık.
34. Watson, Alan. 3/1984. An Approach to Customary Law. University of Illinois Law Review 1984: 561–576.
35. Yasin, Melikşah. 2/2014. Örf ve Adet Kuralları ile İdari Teamüllerin İdare Hukukundaki Yeri [The place of customary rules and administrative practices in administrative law]. İdare Hukuku ve İlimleri Dergisi 15: 29–44.