Joined Cases C-159/10 and C-160/10: Judgment of the Court (Second Chamber) of 21 July 2011 (references for a preliminary ruling from the Verwaltungsgericht Frankfurt am Main (Germany)) — Gerhard Fuchs (C-159/10), Peter Köhler (C-160/10) v Land Hessen (Directive 2000/78/EC — Article 6(1) — Prohibition of discrimination on grounds of age — Compulsory retirement of prosecutors on reaching the age of 65 — Legitimate aims justifying a difference of treatment on grounds of age — Coherence of the legislation)