Do Lawsuits by ENGOs Improve Environmental Quality? Results from the Field of Air Pollution Policy in Germany

It is generally assumed that in EU Member States the right of recognized environmental organizations (ENGOs) to file lawsuits under the Aarhus Convention contributes not only to a better enforcement of environmental law, but also to an improvement of environmental quality. However, this has not yet been investigated. Hence, this paper examines whether 49 lawsuits that environmental associations filed against air quality plans of German cities between 2011 and 2019 had a positive effect on air quality by reducing NO2 emissions in the respective cities. Using a staggered difference-in-differences regression model, we show that, on average, lawsuits against cities’ clean air plans have a negative effect on NO2 concentration in these cities. In fact, the NO2 concentration in cities sued by ENGOs decreased by about 1.31 to 3.30 µg/m3 relative to their counterfactual level.