The jury began as an instrument of the crown, primarily as a tax-collecting device. But over the centuries, it unexpectedly became a guardian of the people's liberty against the government. The case that brought that about, more than any other single case, is called "Bushell's case," which became a landmark for a great principle: Acquittals are final, and jurors can never be punished for returning a verdict that the court thinks is wrong. The ability of the jury to disregard what the judge told them about the law - jury nullification - became a main theme of American jurisprudence for about a hundred years. Trial by jury has been placed in jeopardy recently because the Supreme Court has decided that fewer than 12 jurors is acceptable in criminal cases, and criminal verdicts can be less than unanimous. Also, arguments against the jury in civil cases have been raised by some scholars and judges, contending that juries do not understand cases, and that trial by jury is time-consuming and expensive. To aid in everyone's understanding of some laws, legislators are called upon to be clearer in their legislation.