IANAL, but I thought that the onus was on the prosecution to prove you were guilty as charged, i.e. didn't stab them in self-defence (by proving you stabbed for

IANAL, but I thought that the onus was on the prosecution to prove you were guilty as charged, i.e. didn't stab them in self-defence (by proving you stabbed for some other reason, presumably). Similarly, the prosecution would have to prove you weren't truly desperate if up before the magistrates for stealing food. It might be different in Italy, though.