An overdue post on the Hungarian Supreme Court’s judgment 2020.3.72.a, finding an implied choice of law pro Hungarian law, made by a Serbian and Hungarian party to a contract for agency and business counseling. In the absence of choice of law, per Article 4 Rome I, applicable law would have been Serbian law. Yet the SC held that the conduct of the Serbian business party in the litigation, made for implicit choice of law.
Under Rome I, choice of law may be made and changed at any time during the course of the contract. Whether it can also be made by conduct of litigation is somewhat disputed. Arguments pro rely heavily on a parallel with impromptu choice of court in Brussels Ia, by submission. The Hungarian courts had assessed the merits of the case on the basis of Hungarian law, and the Serbian defendant had engaged in that discussion in a detailed, substantive statement of defence without any objections to Hungarian law being the lex contractus. This, the courts held and the SC agreed, meant parties had made an implied choice of law by their conduct. A change of heart by defendant upon appeal was a unilateral change of law, which cannot bind the parties.
Richard Schmidt sent me the judgment and has additional analysis here– on which I relied for I do not read Hungarian. Scholarship has engaged with the issue and this SC judgment will be highly relevant material for that discussion.
(Handbook of) European Private International Law, 2nd ed. 2016, Chapter 3, Heading 3.2.4.