Muhammad Rabbani, the director of the advocacy organisation Cage, was charged on Wednesday at Bethnal Green police station with 'wilfully obstructing or seeking to frustrate a search examination' under Schedule 7 of the Terrorism Act 2000. Detained at Heathrow Airport in November 2016 on his way back from the Middle East – where, he says, he ‘had secured instructions from a client of ours to take legal action in a case involving torture’ – Rabbani refused to provide border guards with the passwords to his electronic devices. He faces three months in prison and a £2500 fine.

The decision to charge Rabbani comes at a time of widespread controversy over the searching of phones and laptops at borders. Under Schedule 7 of the Terrorism Act, travellers can be questioned at a UK border for up to six hours without the right to remain silent or to receive legal advice. David Miranda, the partner of the journalist Glenn Greenwald, was detained at Heathrow in 2013 and asked to hand over files relating to Edward Snowden. The Court of Appeal later ruled that the use of Schedule 7 powers was incompatible with the right of freedom of expression when used to detain journalists (though it also dismissed Miranda’s appeal against the use of the powers in his case).

In the United States, the Fourth Amendment, which provides protection from 'unreasonable search and seizure', does not apply to 'routine' searches at border crossings. Privacy advocates have argued that searches of digital devices should not be considered 'routine' because of the amount of personal data that phones and computers now contain, which can be copied and permanently stored by border guards. In January, a journalist for the BBC World Service, Ali Hamedani, was forced to hand over his phone and its passcode at Chicago's O'Hare Airport. The Council on American-Islamic Relations has collected complaints from other Muslim travellers. In February, Sidd Bikkannavar, a US citizen and Nasa engineer, was asked to give up the passcode to his phone, violating Nasa’s security rules. 'I do have dark skin,' Bikkannavar said later. 'But I'm not Muslim.' According to Department of Homeland Security data, the number of mobile phone searches of international travellers arriving at US borders more than doubled between 2015 and 2016.

But no US citizens have yet faced criminal charges for refusing to hand over their passwords. (That could be because none has refused; we don't know.) A man was charged in Canada last year for refusing to give up the passcode to his BlackBerry. He pleaded guilty and paid a $500 fine, dashing hopes that his case might be used to test the legality of phone searches at Canada’s borders.

If Rabbani is found guilty when he goes to court on 20 June, a British citizen will have been convicted of a terrorism offence for not giving border guards access to his electronic devices. The precedent will surely be enough to deter all but the bravest travellers from refusing to hand over their passwords.

Why hasn’t there been more of an outcry against Rabbani's arrest and prosecution? Perhaps people expect that the powers will be used only against Muslims. The widespread surveillance of Muslims under the banner of Prevent is a case in point: a mass programme of civil rights restrictions for thousands that goes virtually unnoticed by most of the population. Home Office data shows the racial disparities at play in the implementation of the Terrorism Act 2000: 70 per cent of those arrested in Britain on terrorism charges since 11 September 2001 were non-white. But Schedule 7 powers have also been used against volunteers taking humanitarian aid to refugees in Calais. There’s no way of knowing who will be next.