261Nevertheless, observance of the principle of equal treatment, which prevents comparable situations from being treated differently and different situations from being treated in the same way, unless such difference in treatment is objectively justified, is incumbent on the Commission when it imposes a fine on an undertaking for infringement of the competition rules, as it is on any institution in carrying out all its activities (see Case T-67/01JCB Service v Commission [2004] ECR II-49, paragraph 187 and the case-law cited).