sovereignty, Parliament can enact any primary legislation it chooses. However, the concept immediately becomes problematic when the question is asked, "If parliament can do anything, can it bind its successors?" It is generally held that parliament can do no such thing. Equally, while statute takes precedence over precedent-derived common law and the judiciary has no power to strike down primary legislation, there are certain cases where the supreme judicature has effected an injunction against the application of an act or reliance on its authority by the civil service. The seminal example of this is the Factortame case, where the House of Lords granted such an injunction preventing the operation of the Merchant Shipping Act 1988 until litigation in the European Court of Justice had been resolved. The House of Lords ruling in Factortame (No. 1), approving the European Court of Justice formulation that "a national court which, in a case before it concerning Community law, considers that the sole obstacle which precludes it from granting interim relief is a rule of national law, must disapply that rule", has created an implicit tiering of legislative reviewability; the only way for parliament to prevent the supreme judicature from injunctively striking out a law on the basis of incompatibility with Community law is to pass an act specifically removing that power from the court, or by repealing the European Communities Act 1972. The British legal systems are based on common law traditions, which require: Police or regulators cannot initiate complaints under criminal law but can only investigate (prosecution is mostly reserved for the Crown Prosecution Service), which prevents selective enforcement—e.g., the "fishing expedition," which is often specifically forbidden. Prosecutors cannot withhold evidence from counsel for the defendant; to do so results in mistrial or dismissal. Accordingly, their relation to police is no advantage. Defendants convicted can appeal, but only fresh and compelling evidence not available at trial can be introduced, restricting the power of the court of appeal to the process of law applied. United States Separation of powers was first established in the United States Constitution, wherein the founders included features of many new concepts, including hard-learned historical lessons about the checks and balances of power. Similar concepts were also prominent in the state governments of the United States. As colonies of Great Britain, the founders considered that the American states had suffered an abuse of the broad power of parliamentarism and