Imagine you are in a kangaroo court and the judge and those across the aisle are in bed with each other and have decided -- you are guilty first, even if you didn't actually do anything -- but they also claim that since you could do something in the future, you are guilty. According to Wikipedia, this goes against the long held concept of the 'presumption of innocence' , which harkens back to Roman law: The sixth century Digest of Justinian provides, as a general rule of evidence: Ei incumbit probatio qui dicit, non qui negat 'Proof lies on him who asserts, not on him who denies'.