A. AND OTHERS v. THE UNITED KINGDOM JUDGMENT 73 response to the danger from al-Qaeda, although other States were also the subject of threats, the Court accepts that it was for each Government, as the guardian of their own people’s safety, to make their own assessment on the basis of the facts known to them. Weight must, therefore, attach to the judgment of the United Kingdom’s executive and Parliament on this question. In addition, significant weight must be accorded to the views of the national courts, which were better placed to assess the evidence relating to the existence of an emergency. 181. On this first question, the Court accordingly shares the view of the majority of the House of Lords that there was a public emergency threatening the life of the nation. (iii) Whether the measures were strictly required by the exigencies of the situation 182. Article 15 provides that the State may take measures derogating from its obligations under the Convention only “to the extent strictly required by the exigencies of the situation”. As previously stated, the Court considers that it should in principle follow the judgment of the House of Lords on the question of the proportionality of the applicants’ detention, unless it can be shown that the national court misinterpreted the Convention or the Court’s case-law or reached a conclusion which was manifestly unreasonable. It will consider the Government’s challenges to the House of Lords’ judgment against this background. 183. The Government contended, firstly, that the majority of the House of Lords should have afforded a much wider margin of appreciation to the executive and Parliament to decide whether the applicants’ detention was necessary. A similar argument was advanced before the House of Lords, where the Attorney-General submitted that the assessment of what was needed to protect the public was a matter of political rather than judicial judgment (see paragraph 19 above). 184. When the Court comes to consider a derogation under Article 15, it allows the national authorities a wide margin of appreciation to decide on the nature and scope of the derogating measures necessary to avert the emergency. Nonetheless, it is ultimately for the Court to rule whether the measures were “strictly required”. In particular, where a derogating measure encroaches upon a fundamental Convention right, such as the right to liberty, the Court must be satisfied that it was a genuine response to the emergency situation, that it was fully justified by the special circumstances of the emergency and that adequate safeguards were provided against abuse (see, for example, Brannigan and McBride, cited above, §§ 48-66; Aksoy, cited above, §§ 71-84; and the principles outlined in paragraph 173 above). The doctrine of the margin of appreciation has always been meant as a tool to define relations between the domestic authorities and the Court. It cannot have the same application to the relations between the organs of State at the