CJEU Allows Courts to Scrutinize Methodology and Oversight of Pre-2018 WIBOR

The Court of Justice of the European Union has issued a long-awaited ruling in case C-471/24 concerning mortgage loans based on the WIBOR index. The judgment of February 12, 2026, sets a precedent that could affect thousands of long-term loan agreements in Poland. The Court confirmed that contractual provisions providing for variable interest based on WIBOR and the bank's margin are not inherently prohibited if this index complies with EU law. However, the key significance lies in extending the scope of judicial review to the period before the EU's BMR Regulation came into force in 2018. The WIBOR index was for decades the basis for most mortgages in Poland, and its construction and methodology were the subject of numerous discussions and controversies, especially after the global LIBOR manipulation scandal in the early 2010s. National courts have been authorized to assess two fundamental aspects of WIBOR's historical operation. First, they can examine whether the methodology for determining this rate corresponded to standards later formalized in the BMR regulation. Second, they can verify whether there was real, effective, and independent state supervision over the index-setting process. This means that not only the content of a specific loan agreement is subject to assessment, but also the quality and construction of the mechanism that formed its economic core. Experts emphasize that the older the contract, the more questionable the legal basis for the index used in it may be, since before 2018, WIBOR was not formally recognized as a 'benchmark' under EU law. „Osoby, które zawarły umowę przed latami 2018-2019, mogą powołać się na większą liczbę błędów w umowie i na tej podstawie dochodzić swoich roszczeń przed sądem, niezależnie od samego wyroku TSUE.” (Individuals who entered into contracts before the years 2018-2019 can invoke a greater number of errors in the contract and on that basis pursue their claims in court, regardless of the CJEU ruling itself.) — The CJEU also provided a narrow interpretation of a key provision of the EU directive on unfair terms in consumer contracts. It ruled that the exception from judicial review for clauses reflecting mandatory statutory provisions does not automatically cover contractual provisions setting a variable interest rate based on a benchmark, even if that benchmark is lawful. This decision underscores banks' obligation to fairly and comprehensibly inform consumers about the financial risk they undertake when taking out a variable-rate loan. However, the ruling is not a universal judgment that automatically invalidates all WIBOR-based contracts. Rather, it establishes a legal framework within which borrowers can pursue individual disputes, proving in court that a specific clause in their contract is abusive or that the bank failed to fulfill its information obligation. In practice, this means a wave of new lawsuits, where key evidence will be banks' internal documents and supervisory procedures of the National Bank of Poland and the Financial Supervision Authority from before 2018. A new stage begins in the long-standing battle between borrowers and banks, and its outcome will depend on a detailed analysis of hundreds of thousands of individual cases.