A comparative and historical analysis of the so-called ultima ratio principle reveals that, despite its Latinate veneer, it is neither ancient nor universal, but a recent addition to the German criminal law canon. Upon further inquiry, ultima ratio also turns out to be ill-defined, undermotivated, and toothless, a fundamental legal principle and distinctive feature of criminal law honored in its ubiquitous breach. In the end, the iron legal principle of ultima ratio may appear more like the flexible police maxim of caveat dominus. Its frequent invocation suggests the need to reconceive legal science as a critical analysis of law in general, and of law's supposed principles in particular.