The study approaches the issues when identifying unfair contractual terms, from the perspective of the recent jurisprudential trends in the CJEU jurisprudence, especially in terms of allowing the courts the possibility to approach a contractual term that has not been individually negotiated, but which reflects a rule that, under national law, applies between contracting parties provided that no other arrangements have been established in that respect. The second part of the study is focused on the issues of the unfair character of contractual terms when establishing the mechanism for determining the variable interest rate in a loan agreement and the possibility for the national courts to invite the parties to negotiate with the aim of establishing the method for calculating the interest rate, provided that the national court sets out the framework for those negotiations and that seeks to establish an effective balance between the parties´ rights and obligations.