Working with Inadequate Tools: Legislative Shortcomings in Protection against Ecological Effects of Artificial Light at Night

The fundamental change in nocturnal landscapes due to the increasing use of artificial light at night (ALAN) is recognized as being detrimental to the environment and raises important regulatory questions as to whether and how it should be regulated based on the manifold risks to the environment. Here, we present the results of an analysis of the current legal obligations on ALAN in context with a systematic review of adverse effects. The legal analysis includes the relevant aspects of European and German environmental law, specifically nature conservation and immission control. The review represents the results of 303 studies indicating significant disturbances of organisms and landscapes. We discuss the conditions for prohibitions by environmental laws and whether protection gaps persist and, hence, whether specific legislation for light pollution is necessary. While protection is predominantly provided for species with special protection status that reveal avoidance behavior of artificially lit landscapes and associated habitat loss, adverse effects on species and landscapes without special protection status are often unaddressed by existing regulations. Legislative shortcomings are caused by difficulties in proving adverse effect on the population level, detecting lighting malpractice, and applying the law to ALAN-related situations. Measures to reduce ALAN-induced environmental impacts are highlighted. We discuss whether an obligation to implement such measures is favorable for environmental protection and how regulations can be implemented.