This contribution deals with the legal consequences of unlawful inactivity of the administration. The theme of administrative silence has been subject of studies in national administrative law scholarship for a long time. The approach started with a focus on legal protection, but by now more and more non judicial legal techniques have been introduced to force public administration to act in time. Also arguments and approaches with a more economic and socio-legal character have gained much more influence at the discussion of this issue. Non judicial solutions such as fictitious decision making are chosen more often, also because of international influences and/or obligations (EU directives, OECD reports). The solutions that can be found in the different administrative law systems reflect the way the dominant legal approach looks at the separation and balance of the powers of courts and the administration. Legislators tried to improve the legal position of the applicant who is waiting for the administration to act upon his application by introducing decision making by default. The aim here is to improve the legal position of the applicant by using the requirements following from the principle of legal certainty. The objections by legal scholarship against decision making by default seem to be similar in all EU Members ships involved. Nevertheless, we see an increase of this legal instrument. This is caused by the fact that the same legal scholarship was debating the issue of administrative silence for a very long time without offering effective solutions in time. This could also have been caused by a lack of communication between the administrative law scholarship and the scholarship on the field of law and economics, administrative sciences etc.