Facts
The Green Alliance and Louis Schelbert filed a constitutional appeal with the Federal Supreme Court against the decision of the Grand Council of the Canton of Lucerne to declare the popular initiative "For Air to Breathe" invalid. The Federal Supreme Court partially upheld the appeal and declared part of the initiative valid.Considerations
Federal environmental law does not prevent the cantons from providing for crisis intervention measure packages through generally abstract enactments and making the implementation of measures dependent on intervention limit values. However, the measures provided for in the initiative in the event of a simple exceedance of the immission limit values (ILV) or an exceedance by more than a factor of 1.3 are disproportionate and incompatible with the prohibition of setting new ILVs. However, the canton is fundamentally authorized, within the framework of its competence and subject to the principle of proportionality, to enact short-term measures to combat smog peaks in the event of an exceedance of the ILVs by more than a factor of 1.5.
It is not within the cantonal competence to concretize the scope of application of traffic control measures within the meaning of…