Nowadays, judicial control has developed to such an extent that it can be affirmed that any type of power, statutory or prerogative, will be susceptible to control. The English courts are responsible for managing the manner in which a public power is exercised, with regard to its scope and substance. To achieve this, courts will rely on legislative intent, an area that is the subject of much academic debate, those in favor of the ultra vires theory and those in favor of the common law theory. Whether this legislative intent constitutes a compelling constitutional justification will depend on which grounds of judicial review give those grounds the source of the courts' power of judicial review. There are, however, areas in which courts should or cannot intervene because they are limited, first, by their constitutional role and, second, by their institutional capacity. Courts have a responsibility to ensure that decisions are made according to standards of procedural fairness. Furthermore, they should ensure that a public authority acts within the relevant power or duty. In Ghaidan v Godin-Mendoza, as Lord Nichols said: “Parliament must maintain a fair balance between the competing interests of tenants and landlords, taking into account broad issues of social and economic policy.” Furthermore, the courts are required by the Human Rights Act 1998, as promulgated by the European Convention on Human Rights, to ensure that no public authority can interfere with these rights and that even Parliament is supposed to take them into account. According to Lord Diplock, regarding the government and the executive in general: "They are responsible to Parliament for what they have done so far in terms of efficiency and policy and Parliament is the sole judge of that ; e...... middle of document......the interpretation of laws cannot conflict with the intention of the legislator. However, in a separate case, the court could not interpret section 3 of the Act as this would constitute a violation of the legislative intent. In conclusion, the English courts rely on legislative intent as a compelling constitutional justification for their powers of judicial review. Ultra vires remains an important doctrine because it was set forth in two important cases: R v. Lord President of the Privy Council, ex parte Page and R v. Secretary of State at the Ministry of the Interior, ex parte Pierson. In addition, the courts also rely on the grounds of review as well as the obligations arising from the Human Rights Act 1998. According to Lord Woolf, “our parliamentary democracy is founded on the rule of law. Courts derive their authority from the rule of law and cannot act in a manner that implies its repudiation..”