176In that regard, it should be recalled that EU law requires that administrative procedures are conducted in compliance with the guarantees conferred by the principle of sound administration, enshrined in Article 41 of the Charter. Those guarantees include the obligation for the competent institution to examine carefully and impartially all the relevant elements of the individual case. The right of every person to have his affairs treated impartially encompasses, on the one hand, subjective impartiality, in so far as no officer of the institution concerned who is responsible for the matter may show bias or personal prejudice, and, on the other hand, objective impartiality, in so far as there must be sufficient guarantees to exclude any doubt as to bias on the part of the institution concerned (see judgment of 11 July 2013, Ziegler v Commission, C‑439/11 P, EU:C:2013:513, paragraph 155 and the case-law cited; see also, to that effect, judgment of 11 May 2010, Nanopoulos v Commission, F‑30/08, EU:F:2010:43, paragraph 189).