Elidor asks:

"What are my rights when I refuse to submit to a recorded electronic strip search at an airport? Do they have any right to detain me? Could they single me out for scanning a second time, or are they forced to stick to their alleged "random" sampling?

I'm not going to put up with this sort of harassment from the authorities, but as long as they're still at the low-level random sampling stage of it, I'm willing to attempt to fly knowing I've got a 95%-odd chance of making my flight. I just want to know where I stand if I get unlucky on the day."

The introduction of body scanners in the wake of the failed Christmas Day attack was clearly a rushed attempt to show that something was being done. We at Liberty are far from convinced that this expensive and intrusive technology is necessary or that it will be deployed in a lawful, proportionate and sensitive manner. But the first point to make is that their introduction (so far only at Manchester and Heathrow airports, I believe) did not come with any additional legal obligations on passengers; like all other airport security measures, compliance is simply a condition of flying. So Elidor can refuse to go through the scanner at the expense of missing the flight.

I am doubtful whether the idea of joining the back of the queue and trying a second time would work. The interim code of practice issued by the Department for Transport does not limit the use of body scanners to any strict random method. It simply says that passengers must not be selected on the basis of personal characteristics. I don't see anything unlawful (or even objectionable) in selecting a passenger for a security check on the grounds that they had refused to comply with one moments earlier.

Elidor is also free to leave the airport if he refuses to be scanned, subject to one caveat. schedule 7 of the Terrorism Act 2000 gives the police additional powers at ports (including airports) to detain and question for up to nine hours anyone who they believe is using the port to travel, in order to determine whether that person is a terrorist – as in, is "concerned in the commission, preparation or instigation of acts of terrorism". An officer can question a person on whether or not there are any grounds for suspecting that the person is a terrorist, and can also search the person or anything he owns or is carrying, provided the object to be searched is on a ship or aircraft or the officer believes it has been or will be. The officer can seize anything he finds during his searches for up to seven days, or for as long as he believes it will be needed as evidence in a criminal trial or a deportation decision – whichever is longer. It is a criminal offence to refuse to comply with a search or questioning. The detained person is entitled to telephone a solicitor, but cannot delay answering questions until a solicitor arrives.

These powers are incredibly broad and subject to very few safeguards. The Home Office code of practice says that officers "must use the powers proportionately and should make every reasonable effort to minimise causing embarrassment or offence to a person who has no terrorist connections." It also says that the powers "should not be exercised in a way which unfairly discriminates against a person" on any of a number of grounds, including race or religion, and that the examining officer should bear in mind that the primary reason for using the powers is "to maximise disruption of terrorist movements into and out of the United Kingdom." The breadth of the power, however, means that it will be almost impossible to challenge its use in any individual case.

If Elidor were detained under schedule 7 immediately after refusing to be scanned, and it appeared that this was done as a sanction for failing to comply with security officers or as a deterrent to other passengers, then it could be argued that the detention was unlawful. But since the power could also be used lawfully on someone in these circumstances (indeed it would arguably be sensible to do so if a passenger appears nervous and runs away the moment he or she is selected), it will be very difficult to prove in an isolated case that the officer had an improper motive.

More broadly, it might be possible to argue that the power under schedule 7 is incompatible with article 5 of the European convention on human rights, which states that everyone has the right to liberty and security and that no one shall be deprived of his liberty except in certain limited circumstances. Liberty made a similar argument in respect of stop and search powers under section 44 of the Terrorism Act in the case of Gillan v Metropolitan Police. The House of Lords decided, however, that any deprivation of liberty involved in such a search would not violate article 5 because it would be "in order to secure the fulfilment of any obligation prescribed by law" – a type of detention permitted by article 5(1)(b). Lord Bingham said that the relevant "obligation" was the obligation on all members of the public not to obstruct a constable exercising lawful powers under section 44 of the Terrorism Act. This reasoning is supported by a 1981 European commission case (McVeigh and others v UK) which concerned a power to detain at ports very similar to the power under schedule 7, but in my view it is circular and open to challenge.

The framers of the convention cannot have envisaged that "any obligation prescribed by law" under article 5(1)(b) could include the simple obligation not to obstruct a constable; otherwise, article 5 would permit any police power of detention however broad or unreasonable. Further, although the European court did not rule on article 5 when it considered the Gillan case, it did decide that the sweeping powers created by section 44 violated article 8 (the right to respect for private and family life). Since one of the key factors in the court's decision was the fact that there were inadequate safeguards against abuse – a charge that also applies to schedule 7 – it may now be worth seeking to challenge schedule 7 under both articles 5 and 8.

I suspect, however, that the prospect of a legal challenge, which would probably need to be taken through all of the domestic courts and on to the European court in order to overturn the reasoning in Gillan and McVeigh, is not the type of reassurance that Elidor was after.

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