On this occasion, my leader, the noble Lord, Lord McNally, has wisely disappeared into the bushes leaving me to attempt to explain what is intended by the innocent-looking Amendment No. 63A. I say "attempt" because I make no claim of being master of my brief or of the ramifications of this extraordinarily complicated measure.

Like many noble Lords, I am extremely grateful for the help given by the Foundation for Information and Policy Research in general and in particular on this clause. Mr Caspar Bowden deserves special mention in despatches. However, at this moment I am bound to say that I wonder whether the messenger is up to the task of delivering the purport. The purport is important.

It will help me and, I believe, Members of the Committee if I explain the background to Amendment No. 63A. As I understand it, the Bill provides a series of checks and balances for the citizen and companies against attempts by the state to extract information from them according to the particular needs set out in the Bill.

Perhaps we can consider initially the fact that Clause 8(3) of the Bill allows the first breach of what might be called a basic principle of this measure; namely, that access to confidential information is allowed only on a specific basis where the person or premises are named. That is a fair and basic protection against lazy or malign attempts to get at more than the particular information sought.

Clause 8(3), however, allows a breach of that general principle insofar as the Secretary of State can certificate a warrant which will then mean that it will be puissant in respect of external communications on a trawl basis, or, as some Members of the Committee might prefer, a 12-bore basis rather than a 303, a general rather than a specific intervention into stores of confidential information.

The next exception--a higher level of exception--is the double certification allowed under the provisions of Clause 15(3)(a). That allows not only the trawl of external communications permitted by a certificated warrant under Clause 8(3), but also a trawl of internal communications. It is plain that that goes as far as one might in intervening in the affairs of citizens because the underlying thesis of the Bill is that the powers of intervention should be available only with regard to external communications and not internal communications.

I need to add that a confusion, certainly in the minds of those of us on these Benches and it may persist in the minds of many others, is thrown into this already complicated mix by the provisions of Clause 5(6)(a) of the Bill, which allows an interception warrant to be taken to include,

"all such conduct . . . as it is necessary to undertake in order to do what is expressly authorised or required by the warrant".

As far as we can tell--it will be important for the Minister to clarify this--the provisions of Clause 5(6)(a) allow an interception warrant to be targeted at internal communications as well as external. Clause 8(4) is the only place in the Bill which refers to external and/or internal. So at this stage perhaps I should say that part of the purpose of the amendment is to attempt to draw out from the Government what the combined provisions of this Bill allow and provide for.

One of the main points is to know whether the combined provisions of Clauses 5, 8 and 15 will allow a mixed pool of random internal and external data to be trawled by those who claim to have the necessary warrants or double warrants. Perhaps I can enlarge on that. The meaning of the word "external" is not clear. Again, we will be grateful if the Minister can indicate clearly whether a communication such as an e-mail sent inside the UK to a recipient who is also inside the UK--Birmingham to Manchester--is considered to be an internal warrant despite the fact that the constituent datagrams (or packages of information) may have travelled by way of Honolulu or New York. That is an important question because it is extremely common, I am told, for many domestic Internet communications to be relayed via whichever countries may be concerned because of the connectivity of the Internet, which is a function of commercial alliances as well as the technical infrastructure.

A packet-switched network such as the Internet breaks up its communications into small datagrams--we have had cause to deal with this before--which are autonomously and automatically routed to their destination through an unpredictable sequence of switches. The Bill appears to carry into its body the certificated warrant mechanism of the Interception of Communications Act 1985 to a large degree and, as I say, appears ostensibly, subject to the certification and double certification, to be limited to interception and invasion of external communications.

It is important to appreciate that with any of the collection mechanisms envisaged by the Smith report, to which the Minister referred before the break, for obtaining intercepts directly from Internet service providers (ISPs), it would be very difficult and perhaps impossible to pre-filter or differentiate external from internal communications. Since that distinction is one of the fundamentals of this measure, it is an important point.

That concern is compounded by the fact that, under the Bill, interception warrants are addressed to the agency and not to the telephone company as under the IOC. Furthermore, it is not so far clear whether it is legally necessary to serve a warrant on the Internet service provider if the interception can be achieved entirely covertly. That refers to the wonderful black box which is under remote control. It may be helpful to see one; seeing is believing.

The extra safeguards, which are added by Clause 15 to Clause 14, are intended to ensure that this extraordinarily powerful technique of what is called "super-computer trawling" through communications is not used to circumvent the necessity of an ordinary targeted warrant for persons who are within the British Isles. The idea of the safeguard is that the material cannot be accessed unless it has first been identified by a computer match as falling within the matters described in the certificate.

The situation is complicated--I am sorry that this is a somewhat lengthy introduction to this amendment, but I hope it will be helpful for the amendments with which it is grouped--by the present practice of issuing overlapping warrants. The IOC Act 1985 does not permit key word trawling--that is to say, putting in a word like "Semtex" or "Hezbollah"--through communications acquired under a certificated warrant, which is supposed to be limited to external communications with some exceptions such as anti-terrorist purposes.

The first report of the Interception of Communications Commissioner, the noble and learned Lord, Lord Lloyd, who happily is in his place, published in 1987, stated that,

"it would be possible for the Security Service to get indirectly, through a legitimate examination of certified material, what it may not get directly. In such cases it has become the practice to apply for a separate warrant under Section 3(1) [of the IOC Act], known as an over-lapping warrant, in addition to the warrant under Section 3(2)".

Moreover, even if that overlapping warrant is issued, it is not clear how that would make lawful the practice of searching through the raw material for references to, for example, an address in the United Kingdom other than for counter-terrorism. A normal (non-certificated) warrant allows for the interception of all material pertaining to an address, but it does not make lawful trawling indiscriminately through material in ways that are prohibited. Ostensibly, therefore, the new Clause 15(3) certificate should only grant access to external material. That is mentioned in Clause 8(4). But are overlapping warrants under the IOC to be used to gain access to a trawl of the full range of both external and internal material under current practice?

We have to wonder, given the likely collection mechanism of black boxes stationed at Internet service providers, and given, too, the difficulties of distinguishing external Internet communications from internal, whether the intention here is for the new Clause 15 override certificate to authorise trawling through a mixed pool of raw internal and external communications derived from these packet-stream captures at the ISPs. The danger is that that procedure could in practice become a routine way of performing mass surveillance--the trawling of contents indiscriminately--on the full spectrum of domestic Internet communications.

I conclude by posing some specific questions, and this may be more helpful than my preamble. The first is: what is the purpose of Clause 15(3)? What is its extent and scope? Secondly, how does it interlock with Clause 8(3)? Thirdly, how do each of those, and when taken together, interlock with Clause 5(6)? Fourthly, are the informal overlapping warrant arrangements to continue?

Will it be lawful to trawl through a mixed pool of internal and external communications collected under a certificated warrant--Clause 8(3)? Would the existence of an overlapping warrant allow the lawful examination of internal communications thrown up by such a trawl? Finally, would it be lawful--and is it intended--to serve certificated warrants on internet service providers?

I hope, therefore, that the purpose of this amendment is relatively clear. It is to ensure that material intercepted under a Clause 8(3) certificated warrant, which is supposed to be limited to external communications with some leeway under Clause 5(6) permitting the unavoidable collection of extraneous material, is filtered so that the material that is looked at, read, or listened to is actually limited to external communications. I apologise again for the length of my speech in moving this amendment. I have done my level best as regards its complexity. I must now leave the Minister to respond as best he can. I beg to move.