Part of European Union (Notification of Withdrawal) Bill – in the House of Commons at 3:15 pm on 8 February 2017.
According to my reading of the new clause, the sanction is that until the Prime Minister has given the undertaking, she cannot proceed with giving notice under article 50, which I suspect is the intention of those who tabled the new clause. These new clauses are festooned with mechanisms for not giving notice under article 50, which is the entire purpose of the Bill.