A27 In the United Kingdom the power to negotiate and conclude treaties is the exclusive preserve of the executive branch of the government, which, acting on advice, can bind the United Kingdom on an international level.225 This is (theoretically) balanced by the dualist approach to international law whereby a treaty has no effect on a domestic level until incorporated into legislation. Thus should the terms of the treaty require alteration of domestic law, these obligations cannot be performed without legislative action.
A28 As a matter of long-standing practice the government lays before Parliament as Command Papers all treaties signed by the United Kingdom, but only after their entry into force.226 Treaties may also be tabled in accordance with the Ponsonby Rule which was introduced in 1924 by the British Under-Secretary of State for Foreign Affairs. This convention
obliges the British Government to let treaties lie on the table of the Parliament for 21 days after signature and before ratification and to submit important treaties to the House of Commons for discussion. It applies only where a treaty places “continuing obligations” on the United Kingdom, where a further formal act to signify commitment is required after signature and where the matter is not one of “urgency”. In 1990–91, the Select Committee on the European Communities of the House of Lords estimated that approximately one quarter of the United Kingdom treaties were subject to the Ponsonby Rule.227
A29 However, the Ponsonby Rule can be described as ineffectual for a number of reasons. First, the voluntary nature of the rule has meant it has fallen into disuse: recent governments’ statements have made it clear that the rule is not regarded as a binding convention and departures are made from it on grounds of expediency.228 This demonstrates that for a tabling procedure to be effective it should be established on a more formal basis.
A30 Further, where a treaty is tabled in accordance with the Ponsonby Rule, the text is tabled without explanation of its meaning, purpose or reasons for its ratification. This significantly detracts from the effectiveness of Parliament’s involvement in treaty making. In addition,
[t]he Government is not bound to find parliamentary time to devote to a motion deploring the Government’s intention to ratify a treaty. If time were found it is unlikely that the Government would be defeated in the House of Commons. The Government might in the face of parliamentary disapproval change its mind but this is unlikely.229
A31 Interestingly, although the Westminster Parliament has traditionally played a very limited role in treaty making and implementation, it does possess the power to limit the executive in its capacity to enter into certain treaties. However, this power does not seem to be invoked often. An example of the exercise of this power is section 6(1)–(2) of the European Parliamentary Elections Act 1978 (UK) which provides:
(1) No treaty which provides for an increase in the powers of the European Parliament shall be ratified by the United Kingdom unless it has been approved by an Act of Parliament.
(2) In this section ”treaty” includes any international agreement, and any protocol or annex to a treaty or international agreement.230
A32 The United Kingdom’s membership, since 1973, of the European Economic Community (now the European Union or EU) has had a significant effect upon the traditional supremacy of Parliament which is now overshadowed to a great extent by EU law. The Treaty of Rome established the Community (or Union as it now is) with a written constitution and provided that the United Kingdom Parliament has accepted that the Treaty and Community legislation shall prevail in cases of inconsistency between Community law and domestic law or practice.231 Enactment of EU legislation is preceded by rigorous scrutiny and consultation involving the European Council, Commission and Parliament.232
A33 Since the United Kingdom’s accession to the EU the government has deposited proposals in both the House of Lords and the House of Commons, which are subjected to extensive scrutiny by select committees in both chambers. After investigation, reports are made for debate on the floor of both Houses. The role of the United Kingdom Parliament in the consideration of and debate about EU legislation is a direct contrast to the lack of effective parliamentary involvement in treaty making with non-Member States.233
A34 It is perhaps the binding nature and far-reaching implications of the EU law which has prompted the comprehensive scrutiny of proposals. The supremacy of EU legislation is illustrated by the House of Lords decision in R v Secretary of State ex p Factortame No 2  1 AC 603 where it effectively held that the provisions of an English statute were not conclusive in a case of conflict with Community law.234 Arguably the Factortame judgment signals the need for principles of constitutional law to better reflect the reality in which they operate.
A35 In 1996 Lord Lester QC introduced the Treaties (Parliamentary Approval) Bill (HL) 1995/96. The Bill was passed through all stages in the House of Lords, receiving its second reading on 28 February 1996 after substantial debate. Although the Bill has now lapsed, it is still useful to note the Bill’s proposed reforms. In relation to the ratification process, the Bill proposed introducing a requirement that concluded treaties subject to ratification be approved by Parliament before they are ratified. In effect the Bill would apply to about a dozen, mostly multilateral treaties, each year which require ratification before coming into force.235
A36 The proposed procedure would have been to require the tabling of the treaties in Parliament, along with an explanation of the object and purpose of the treaty, the reasons for the proposed ratification, and the likely benefits and disadvantages of becoming party to the treaty.236 Approval of both Houses of Parliament would have been required before the government could ratify the treaty.237 If either House objected to ratifying a treaty, a resolution confirming this must be passed within 21 sitting days of the treaty being tabled.238 The Bill also provided for an exception in the case of urgent treaties.239 In that situation the Secretary of State was to notify both Houses of Parliament of the decision and the reasons for it.
A37 A proposal in the Bill which has been implemented is the use of explanatory memoranda to improve the information about treaty matters which is provided to Parliament by the executive. All international agreements signed after 1 January 1997 and laid for 21 sitting days under the Ponsonby Rule, namely those agreements concluded subject to ratification, accession, acceptance or approval, are to be accompanied by an explanatory memorandum.240 As the Guidelines on Explanatory Memoranda for Treaties, created by the Foreign and Commonwealth Office, explain, the explanatory memoranda will bring to the attention of Parliament the main features of the treaty with which it is laid, including:
benefits and burdens from becoming a party to the treaty,
reservations and declarations,
means of implementation, and
Preparation of explanatory memoranda is the responsibility of the department which has the main policy interest in a particular treaty.