Reijer’s current research focuses on questions surrounding digitization and constitutional democracy. His most recent book is ‘Artificiële intelligentie en de rechtsstaat’ (Artificial intelligence and the constitutional state). For his article digitalisering en de (dis)balans binnen de trias politica’ (digitization and the (dis)balance in the separation of powers) Leiden Law School awarded him the Meijers prize for the best published article from each faculty research programme and the Van Wersch Springplank prize for the best juridical article published in 2020.