3. c. 94) was an Act of the Parliament of Great Britain that required and established a set procedure for the indefinite detention of mentally ill offenders.

If the judge presiding over the case thought that it would be dangerous to release the defendant and wanted him detained, a separate civil commitment hearing had to be held before the person could be incarcerated.

If it could be successfully argued that a lunatic committed a crime during a brief moment of sanity, then it was considered acceptable to convict the defendant, allowing the authorities to detain that person for the good of society.

His statement at the time of his arrest was: "It is not over yet – there is a great deal more and worse to be done" which the prosecution used to argue that he was sane enough to plan the event and then carry it to fruition.

This charge proved to be critical in determining the result of his case because it entitled him to several rights that were not given to criminals who had attempted to kill an ordinary person.

"[2] In essence, the Criminal Lunatics Act required the detention of someone who had committed a crime in a bout of insanity rather than leaving it to the discretion of the judge and jury.