The owner of a French patent for a storm water treatment method and horizontal separator launched a patent infringement action against the company MSE.

Firstly, measures of interim prohibition were ordered by a summary proceedings judge.

The Court of first instance considered that the evidence of prior art produced by MSE to challenge the validity of the patent were insufficient.

Thus, in its decision dated October 11, 2013, the Court confirmed the validity of the patent and ruled that MSE had indeed infringed such patent.

In appeal however, MSE produced new evidences of prior art. The Paris Court of Appeal took them into account and, after three years of proceedings, cancelled the patent for lack of inventive step.