It notes the role of 'dangerousness' as a concept in recent criminal legislation and research: the Butler committee report in England, France's 'Security and Liberty' law, Ohio's dangerous offender law, and others. It then cites scholars who have expressed reserve against attributing definitive qualities to the notion of dangerousness, warning against trying to endow legal validity to a vague popular notion. The suggestion that the myth of offender dangerousness prediction is being exploited for politically repressive ends is also raised. The author then reviews arguments stating that a scientific determination of dangerousness is not possible, again quoting extensively from former literature. Discussion also concerns the dilemma which some American laws have created by placing responsibility for determining dangerousness at the discretion of police and judicial officers rather than exclusively upon scientific professionals. In conclusion, the author emphasizes that even though society's fears need to be placated and citizens protected from those known to be potentially dangerous, the state must protect the liberty and the interests of the subjects involved. It must guard against the danger of abusing its power and exercising violence and repression over citizens deemed dangerous for reasons of political and economic expediency. A total of 18 footnotes are provided.