54Under the case-law, the institutions have freedom of choice as to the organisation and management of staff, and notably, as a consequence of that, are not obliged to adopt one particular appraisal and regrading system rather than another (see, to that effect, judgment of 14 February 2007, Simões Dos Santos v OHIM, T‑435/04, EU:T:2007:50, paragraph 132 and the case-law cited), provided that they observe the general principles of EU law, in particular the principle of equal treatment.