I respectfully invite the noble Lord to read fully the debate at Second Reading, where that was explained by a number of noble Lords.
Amendment 5 would take out subsections (5) and (6). The first reason to do that is to avoid the problem which could result in us running out of time; that is, the matter having to go to the other place and then come back. We have the safeguard that that amendment would require that the extension agreed by the Prime Minister could not end earlier than 22 May 2019. That is an important part of the amendment that is about to be proposed. We are safeguarding ourselves against leaving without a deal.
Legal certainty comes into it for several reasons. First, if noble Lords look at the Bill, they will see that subsection (6) refers to the condition in subsection (7) being operated because,
“the European Council proposes an extension of the period specified in Article 50(3)”.
There may be a question about whether there has in fact been a proposal.