European Union – Employment. Articles 6(b), 16(b) and the first paragraph of art 19 of Directive (EC) 2003/88 should be interpreted as not precluding national legislation which laid down, for the purpose of calculating the average weekly working time, reference periods which started and ended on fixed calendar dates, provided that that legislation contained mechanisms which made it possible to ensure that the maximum average weekly working time of 48 hours was respected during each six-month period straddling two consecutive fixed reference periods. The Court of Justice of the European Union so held in a preliminary ruling in proceedings concerning the reference period used to calculate the average weekly working time of active officials of the French national police force.