My Lords, the arguments for and against a definition of national security have been considered at length both here and in the other place over the years, including in the Bill’s Committee stage in the other place. Neither House has been persuaded of the necessity of such a definition.
If the Committee will forgive me, I do not intend to rehearse previous discussions in full, but suffice it to say that it has been the policy of successive Governments not to define national security in statute. National security is one of the statutory purposes of the security and intelligence agencies. Threats to national security are, as we have heard, constantly evolving and difficult to predict, and it is vital that legislation does not constrain the security and intelligence agencies in their ability to protect the public from new and emerging threats.
The noble Lord, Lord Lester, and the noble and learned Lord, Lord Brown of Eaton-under-Heywood, made a very important point about the European convention. However, I think the key point is that to define national security in statute could have the unintended effect of constraining the ability of the security and intelligence agencies to respond to new and emerging threats to our national security.
My noble friend Lord Swinfen made an important point which was echoed by the Solicitor-General in the other place. Who could have imagined a few years ago cyberattacks of the nature and scale that now threaten us?
As I understand it, the noble Baroness, Lady Jones, is concerned with the purpose of national security being subject to too broad an interpretation in the Bill. I hope, however, that she will be reassured by the role of the judicial commissioners. They will oversee the use of these powers and will ensure that they are used only when it is necessary and proportionate to do so. The commissioners are the ultimate check against abuse. We need to remember that all the most intrusive powers in this Bill that may be used for the purpose of national security are subject to the double lock. That means that the Secretary of State and a judicial commissioner must consider whether their use is necessary and proportionate. The activities of the security and intelligence agencies will be subject to retrospective oversight by the Investigatory Powers Commissioner and, of course, the Intelligence and Security Committee of Parliament. Should the Government ever treat national security as a kind of blank cheque, I have no doubt that the ISC and the IPC would make clear their position in their reports.
In view of the considerable time that Parliament has spent considering this question in the past, the conclusion it reached and the arguments advanced during this debate, I invite the noble Baroness to reconsider and not to press her amendment.