While constitutionalisation constitutes a common phenomenon of European administrative legal orders, German administrative law may be regarded as probably the most constitutionalised administrative law system, culminating in Fritz Werner‘s understanding of ‘Verwaltungsrecht als konkretisiertes Verfassungsrecht‘ (‘administrative law as concretised constitutional law‘). Against this background, the article in a first step not only elaborates on the phenomenon of constitutionalisation, but also qualifies the widespread constitutionalisation thesis. The latter has moreover been questioned by two megatrends impacting all European administrative legal orders, namely their Europeanisation and their alleged emancipation from the Constitution. Whether this means a deconstitutionalisation of administrative law and how these tendencies might be reconciled, will be discussed in further parts of the article.