may be used lawfully without breaching copyright, but a device to detect radar signals so as to avoid speed camera/red light infringement systems would have no other purpose than assisting drivers to evade detection. But note that the act incited must be a crime by the person incited so any alleged breach of copyright would have to be criminal, and the defendant would have to know all the material facts that would make the incited person's behaviour criminal, but not that the behaviour was a crime (see the public policy ignorantia juris non-excusat which prevents ignorance of the law from being an excuse). In R v Whitehouse an uncle did not incite his 15-year-old niece to incest because, if the incitement had succeeded and she had submitted to intercourse, she would not have committed an offence. This applied R v Tyrell which stated that where a statutory offence is designed to protect a particular class of individuals against themselves, they cannot, as the victims, commit such offences against themselves. In Tyrell, the girl was not guilty of inciting the man to have under-age sex with her, since the girl could not herself be guilty of the full offence. Impossibility If X incites Y to kill Z but, unknown to both of them at the time, Z had already died, it would be impossible to kill Z and so no crime of incitement would have been committed. Apart from simple situations such as this, the current law is difficult. R v Fitzmaurice allows the impossibility defence, but its scope is quite limited. X planned to collect a reward from a security firm by informing the police of the existence of a conspiracy to rob a security van. He recruited the defendant who thought he was engaging men for this robbery. Subsequently, the conspirators were arrested by the police. The Court of Appeal held that the test was to decide what sort of conduct was incited, attempted or the subject of a conspiracy. If the evidence shows incitement in general terms, e.g. to rob a security van, this is always possible, whereas if the subsequent agreement relates to a specific but fictitious crime, there might be an acquittal. In DPP v Armstrong [2000] Crim LR 379, 1999 EWHC 270 (QB) it was held that impossibility of the commission of the offence incited was irrelevant to guilt. Soliciting to murder The offense of