Is it unfair to account for compatibility with design characteristics of copetitors?

The question of whether or not the adaption of design features, in order to integrate a product into a series or a system developed and designed by a third party, offends the principle of fair competition has been under heavy dispute in the past.

While the BGH had ruled in the decision "Klemmbausteine II" (Urt. v. 7.5.1992 - I ZR 163/90, GRUR 1992, 619 = WRP 1992, 642)that such an integration into a series of a third party (in the case at issue, the products were plastic bricks matching Lego breaks constitutes an unfair profiting of the achievements of that third party.

However, this rule was put into perspective with the subsequent decision “Klemmbausteine III” (I ZR 30/02) and "Modulgerüst" according to which this subsequent protection against inserttion into a series of a third party should be at least limited in time. According to the Senate, the term of protection should be based on the term of protection of similar industrial property rights such as patents or registered designs. However, a legitimate interest of the author of a series of product to be protected against insertions into the series was recognized.

The two recent decisions “Regalsystem” (I ZR 136/11), and "Einkaufswagen III" constitute surprising turning point in this line of decisions. According to the decision “Einkaufswagen III”, the fact that an interest of customers in optically compatible products in view of the need of replacement or enlargement exists is no indication for an inappropriate exploitation of the valuation of the imitated product, but rather an indication to the contrary. If a need for replacement using optically compatible products exists of the side of the customers, an inappropriate exploitation of the valuation of the counterfeit product may be excluded even if the aesthetic design features are adopted almost identically.

One decisive factor is the question whether or not the salability of a product with differing design features would be reduced as compared to the product with imitated design features (BGH “Regalsystem” I ZR 136/11).