3 GDPR provisions stipulate that the controller must check whether its processing complies with the principle of fairness (German: “Treu und Glauben”):

Art. 5 I a: ”Personal data shall be processed […] fairly […].”

 

Art. 13 II: The controller shall provide the data subject with additional information “necessary to ensure fair and transparent processing”.

 

Art. 14 II: The controller shall provide the data subject with additional information “necessary to ensure fair and transparent processing in respect of the data subject”.