The determination of the irreversible cessation of brain function (ICBF) is conducted in Germany according to the guideline of the German Medical Association, which is currently its fourth update issued in July 2015. This article provides an assessment of the current situation including an international comparison. International case reports with allegedly incorrect ICBF diagnosis are reviewed from the point of view of the German guideline. These case reports underpin the validity of the German guideline, especially its following provisions: (1) in patients with known or suspected adaptation to chronic hypercapnia, apnea cannot be diagnosed as usual; therefore in such a case the proof of cerebral circulatory arrest is mandatory; (2) if perfusion scintigraphy is used for proof of cerebral circulatory arrest, only validated lipophilic radiopharmaceuticals are allowed. This is compatible with new research data which indicate that cellular function can be reactivated for several hours after circulatory arrest but not the brain function. The recently updated recommendations of the German Society for Clinical Neurophysiology and Functional Imaging (DGKN) for ancillary testing include editorial adaptations (e.g., the more precise specification of the electrode positions for electroencephalography), standards of display screen with digital electroencephalography and age-related minimum values of mean arterial pressure for Doppler and duplex sonography in children. The novel requirements regarding the institutional organization of ICBF diagnostics in Germany issued in the "Second law on the amendment of transplantation law-improvement of the cooperation and the framework for organ donation" that became effective recently are presented and discussed critically in this review.