German atomic law requires the precautions against damage that are necessary nach dem Stand von Wissenschaft und Technik, by the state of science and technology. In 1978 the Federal Constitutional Court ruled on the fast breeder reactor at Kalkar and said how far that duty goes. To demand that every risk be ruled out absolutely hieße die Grenzen menschlichen Erkenntnisvermögens verkennen, would misjudge the limits of human knowledge. Uncertainties beyond dieser Schwelle praktischer Vernunft, this threshold of practical reason, must be borne by all citizens.
The German word Restrisiko, residual risk, is often traced to this decision. It does not appear in the text.