For the purposes of the individual assessment of facts that might constitute serious reasons for considering that an applicant has been guilty of acts contrary to the purposes and principles of the United Nations, has instigated such acts or has otherwise participated in such acts, the fact the applicant was convicted by the courts of a Member State of participating in the activities of a terrorist group is of particular importance, as is a finding of a court or tribunal that the applicant was a member of the leadership of such a group, and there should be no requirement to establish that the applicant instigated a terrorist act or otherwise participated in it.