Mangold was a 56-year-old German man employed on a fixed term contract in a permanent full-time job. According to German law, fixed term contracts are unlawful unless they can be objectively justified. However, if the employee is over 52, that requirement does not apply.
The ECJ held in its judgment the German law contravened the Employment Equality Framework Directive, even though it did not have to be implemented until the end of 2006. It said that, in general terms, legislation that lets employers treat people differently because of their age “offends the principle” in international law of eliminating discrimination on the basis of age. The ECJ ruled that national courts must set aside any provision of national law which conflicts with the directive even before the period for implementation has expired.
75. The principle of non-discrimination on grounds of age must thus be regarded as a general principle of Community law. Where national rules fall within the scope of Community law, which is the case with Paragraph 14(3) of the TzBfG, as amended by the Law of 2002, as being a measure implementing Directive 1999/70 (see also, in this respect, paragraphs 51 and 64 above), and reference is made to the Court for a preliminary ruling, the Court must provide all the criteria of interpretation needed by the national court to determine whether those rules are compatible with such a principle (Case C-442/00 Rodríguez Caballero  ECR I-11915, paragraphs 30 to 32).
76. Consequently, observance of the general principle of equal treatment, in particular in respect of age, cannot as such be conditional upon the expiry of the period allowed the Member States for the transposition of a directive intended to lay down a general framework for combating discrimination on the grounds of age, in particular so far as the organisation of appropriate legal remedies, the burden of proof, protection against victimisation, social dialogue, affirmative action and other specific measures to implement such a directive are concerned.
Because it recognised that equal treatment is a general principle of EU law, Mangold v Helm is significant for three critical reasons. First, it means that a claim for equal treatment is available for private citizens on a horizontal direct effect basis. It is unnecessary to wait for a Directive to have been implemented before making a claim to have caused discrimination. Second, it means that member state and EU legislation, like Directives, may be challenged on the ground that they fail to comply with the general principle of equal treatment. Third, because the court did not limit its remarks to the particular grounds of discrimination presently found in the equal treatment Directives (on sex, race, and disability, belief, sexual orientation and age) it follows that claims against unjustified discrimination on the basis of other characteristics may be possible (such as caste, education, property or military service). It would be likely to reflect the jurisprudence from the European Convention on Human Rights, where article 14 which lists similar grounds to those already in the EU Directives but also adds "or other status".