European Union (Withdrawal) Act 2019
The European Union (Withdrawal) Act 2019 (c. 16), commonly referred to as the Cooper–Letwin Act, was an act of the Parliament of the United Kingdom that made provisions for extensions to the period defined under Article 50 of the Treaty on European Union related to the United Kingdom's withdrawal from the European Union.
Source: Wikipedia — European Union (Withdrawal) Act 2019 (CC BY-SA 4.0)