Filter specialists from the Freudenberg Group discovered the violations and have filed patent suits against five exhibitors from the Far East. In addition, the company has started legal action against the supposed counterfeiters.

Five companies from Korea, Taiwan and China apparently violated three different Freudenberg patents, including the "sealing lip system", a thermoplastic elasticized clamp with a sealing lip which is installed at the end of the filter against the housing to seal it. The second patent specifies that a nonwovens or plastic overlapping flap is adhered to the filter. In the third patent, the distribution of regular and irregular filter media pleat distances is described in combination with two guide pins for protection against turning.