The Federal Labour Court ruled by judgement dated 23 March 2011 (docket no. 4 AZR 366/09) that qualified differentiation clauses in collective agreements in the form of so-called "adjustment clauses" (Spannklausel) are invalid. Since August, the reasons for the judgement to this long-awaited decision of the Federal Labour Court have become available:
In the said case the parties to the litigation had concluded a collective agreement on the granting of a recuperation allowance of 260 euro per year, which was to be granted exclusively to union members (so-called simple differentiation clause). According to the collective agreement, should the employer grant amounts or benefits to non-union members corresponding to or exceeding this claim, the employer's payment to the union members should additionally increase accordingly (so-called qualified differentiation clause in the form of an adjustment clause).
In the decision the Federal Labour Court confirmed its previous case law to the effect that the agreement of a simple differentiation clause which envisages special benefits only for union members is permissible. In contrast, however, it deemed a qualified differentiation clause in the form of a so-called adjustment clause to be invalid. Namely, such an agreement exceeds the collective bargaining power of the parties to the collective agreement. They are not authorised to restrict the employer's individual contractual structuring possibilities with mandatory effect, especially concerning employees who do not belong to an organisation or who are members of in another organisation. The adjustment clause, however, – as intended – makes it legally impossible for the employer to pay non-organised employees the same pay as that of union members, even if it intends to put them on an equal footing. Such a qualified differentiation clause is therefore invalid.

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