By Catherine Mayer
November 19, 2014

As an idea it appears beautifully simple: stop potential terrorism by stopping potential terrorists at your borders—even if they’re your own citizens. Canada has already started revoking the passports of its nationals who are thought to have traveled to join Islamic extremist groups in Syria and Iraq. Australia is piloting new legislation to impose prison sentences of up to 10 years on anyone returning to the country from overseas conflict zones who cannot prove a legitimate reason for the trip. And on Nov. 14 during Prime Minister David Cameron’s sojourn in Australia for the G20 summit, he unveiled his own plans to limit the increasing flow of “gap-year jihadis” by preventing Britons from coming home to the U.K. after a spell in the ranks of ISIS or some other violent Islamist organization.

Australian lawmakers warmly applauded Cameron’s proposals, whilst calls for the U.S. to adopt similar measures are growing louder. Yet reactions back in Britain are mixed. Three overlapping concerns dominate the debate: are such measures just, do they square with international law and would they really work?

Nobody denies the scale of the problem. The U.K. authorities estimate that between 500 and 600 Britons have traveled to Syria and Iraq to wage jihad. More than half of these have already returned to the U.K. while a further 25-30 are thought to have died in battle. That leaves around 250 whose eventual homecoming presages a raft of possible dangers and pressures. The security services are already stretched thin trying to keep tabs on radicals whose foreign travels have furnished them with the contacts and the skills to launch attacks at home or narratives to help the ISIS recruitment drive. Deradicalization programs have proved effective but struggle under the weight of numbers.

From that perspective, says Jonathan Russell, the political liaison officer of the counter-terrorism think tank Quilliam Foundation, there could be short term gains from restricting the influx of returnees. The British government plans to publish its proposed new bill before the end of November and get it onto the statute books by January, enabling officials to turn away suspect Britons for two years at a time if they refuse to submit to tough re-entry conditions such as facing prosecution or submitting to close supervision. The law is also expected to penalize airlines that fail to observe no-fly lists.

“It’s likely to stop dangerous people entering the U.K. and ease the pressure on the security services and their surveillance operations and make sure they can’t commit terrorist attacks in the U.K. in the two years they’re held up.” says Russell, but he is unconvinced by the move. “If we’re looking for longterm security I can’t see why it would have any impact.”

Russell is concerned that a large number of the Britons trying to return home would likely do so via Turkey, and find themselves stranded there, creating fresh problems and a diplomatic headache with Turkey which is likely to be at best an unpredictable partner in any resulting negotiations. Sara Ogilvie, policy officer for the U.K.-based human rights organization Liberty raises a different objection: excluding Britons from Britain is, she believes “clearly unlawful.” “If the result is to render someone stateless that will be a breach of our international obligations and will be subject to challenge,” she says.

Britain’s Supreme Court is already testing a related case, of a Vietnam-born naturalized Briton, known for legal reasons only as “B2,” who was stripped by the British government of his adopted citizenship in 2011 because of suspicions he was an al Qaeda supporter. Vietnam refuses to accept he is a Vietnamese national, so the British decision made B2 effectively stateless, in potential contravention of a key United Nations convention. When the Cameron first mooted new, tougher counter-terrorism laws in September, he floated the notion of permanently disowning British-born U.K. nationals involved with ISIS but has since accepted that there is no legal way to do so. The idea of two-year renewable exclusion orders to keep out British jihadis is intended to comply with international law. Ogilvie is skeptical: “If you’re a U.K. citizen but you can’t get into the U.K. what’s the point of you having U.K. citizenship? You don’t get the value of it. So we think that will definitely be challenged in the courts.”

The issue of the U.K’s relationship with the European Union is also complicated. Currently U.K passport holders have the right to travel throughout the E.U. but it is not clear how exclusion orders will affect their rights to remain in the E.U.

Ogilivie also argues that the proposed law infringes the values of democracy and the rule of law that it purports to safeguard. This is an issue Quilliam’s Russell also raises. The measure and the rhetoric around it “feeds into the narrative of the West being at war with Islam,” he says, adding an important clarification. “I wouldn’t say that counter-terrorism legislation makes people radical. It is a grievance that is exploited by radicalizers.” In his view, rather than seeking to exclude returning fighters, the U.K. authorities should do as much as possible “to engage with them ideologically, change their views and deradicalize them.”

On this point Margaret Gilmore, senior associate fellow of the Royal United Services Institute, RUSI, agrees, but she sees a potential benefit from the measure. “There’s been a lot of discussion in the Muslim community here, with some people saying if people want to come back it’s going to be more difficult now because they will be stopped and questioned,” she explains. “Yes they will be stopped and questioned but there will be some who welcome the fact that they will be stopped and questioned and can say ‘look I really have moved on, these are the reasons, I want to go back to my family, move back into the mainstream of thinking’.”

In this scenario, the kinds of returnees who are susceptible to rehabilitation will find it more easily. “It’s a very clear route to come back in and be helped back into the mainstream,” Gilmore says. The jury is out on that point, or may be soon enough.

Contact us at editors@time.com.

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