International organizations — European Union — Membership — Withdrawal — Treaty on European Union, Article 50 — Notification by United Kingdom of its intention to withdraw from European Union — Whether notification to withdraw made pursuant to Article 50 may be unilaterally revoked by United Kingdom — Whether unilateral revocation of withdrawal notification subject to other conditions — Deadline for revocation — Effects of revocation of Member State’s intention to withdraw from European Union

Treaties — Withdrawal — European Union Treaties — Treaty on European Union, Article 50 — Right of withdrawal from European Union — Notification of Member State of its intention to withdraw — Whether notification to withdraw made pursuant to Article 50 may be unilaterally revoked by Member State concerned — Whether unilateral revocation of withdrawal notification subject to other conditions — Deadline for revocation — Effects of revocation of Member State’s intention to withdraw from European Union

Treaties — Vienna Convention on the Law of Treaties, 1969, Articles 54, 65, 67 and 68 — Withdrawal of a State from a treaty — Whether notification by State of its intention to withdraw from treaty may be unilaterally revoked by that State — European Union — Treaty on European Union, Article 50 — Whether Article 50 of Treaty on European Union constituting lex specialis in relation to Articles 65, 67 and 68 of Vienna Convention on the Law of Treaties

Treaties — Interpretation — European Union Treaties — Treaty on European Union, Article 50 — Right of withdrawal from European Union — Notification of Member State of its intention to withdraw — Whether notification to withdraw made pursuant to Article 50 may be unilaterally revoked by Member State concerned — Whether question of interpretation of Article 50 by referring court admissible — Wording of Article 50 and objectives pursued — Context and European Union law provisions as a whole — Origins of Article 50 — Articles 65, 67 and 68 of Vienna Convention on the Law of Treaties, 1969 — The law of the European Union