Human rights — Admissibility of authors’ communication to Human Rights Committee — Consideration of merits — Right to freedom of thought, conscience and religion — Assessment of claim of conscientious objection to military service — Whether within ambit of Article 18 of International Covenant on Civil and Political Rights, 1966 — Whether restriction on authors permitted under Article 18(3) of Covenant — Whether necessary — Whether State Party violating its obligations under Article 18(1) of Covenant — Effective remedy