" ... The entitlement to disclosure of relevant evidence is not an absolute right. In any criminal proceedings, there may be competing interests, such as national security or the need to protect witnesses at risk of reprisals or keep secret police methods of investigation of crime, which must be weighed against the rights of the accused. In some cases, it may be necessary to withhold certain evidence from the defence so as to preserve the fundamental rights of another individual or to safeguard an important public interest. However, only such measures restricting the rights of the defence which are strictly necessary are permissible under Article 61. Moreover, in order to ensure that the accused receives a fair trial, any difficulties caused to the defence by a limitation on its rights must be sufficiently counterbalanced by the procedures followed by the judicial authorities."