Lawfulness and possible unfairness of variable interest rate clauses

The article deals with legal issues connected with existence of variable interest rate credit contracts. It endeavors to identify and resolve the most controversial issues arising out of the use of this legal construction. The discussion focuses on three main legal aspects. The first one refers to the permissibility of inserting such clauses into the contracts, which is derived from the principle of the freedom of contract. Subsequently, such availability is evaluated with connection to the "atypical" contracting situation - i.e. the introduction of variable interest rate by the means of standard forms. The question of the legitimacy of such unilateral declaration of will is elaborated on the basis of Article 3841 of the Polish Civil Code. Finally, the issue of a minimum content for the modification clauses is addressed. The analysis of this problem focuses on the criticism of the "formalistic approach" that advocates for nullity of the clauses that do not fulfill special requirements. Instead, the paper advocates the theory in which the unfairness of a clause, and therefore its nullity, is determined on the basis of the control procedures in the Civil Code, in particular the control procedure of unilaterally imposed contractual terms.