In medieval England, those who had been forced to “abjure the realm” and go into exile would be required to walk barefoot, carrying a wooden cross, to the nearest port. There, they were to take passage on the first available ship; until they were able to do so, they had to wade, daily, into the sea, as testimony to their willingness to leave the country.

This specific provision is absent from the Home Secretary’s proposed expansion of her powers to arbitrarily deprive Britons of their citizenship – expected to be considered again by MPs this week. But the echo of the medieval punishment of banishment in the modern measure of ‘citizenship-stripping’ is impossible to ignore. It has perhaps been best summed up by the Supreme Court of the United States, which has described the practice of making someone stateless by removing their citizenship as “a form of punishment more primitive than torture.”

And in some ways, the modern procedure of which Theresa May is so fond is worse than its centuries-old equivalent. By and large, those medieval unfortunates forced to abjure the realm were not at risk of further punishment from the state provided they stayed out of the country. The same cannot be said of those who have been deprived of British citizenship under the current government's existing, limited powers, which they are currently seeking to expand. According to the Bureau of Investigative Journalism, of the estimated 37 people who have had their passports torn up by the current British Home Secretary, two have so far been killed in covert US drone strikes, and one has been kidnapped and “rendered,” also by the US.

Conveniently for both governments, the removal of British nationality from these people means that the obligations on the British authorities – in terms of the provision of consular services to those detained, or the carrying out of an inquest into the deaths of those killed overseas – are lifted.

As leading lawyer Baroness Kennedy QC put it during the Lords debate on these proposals, contained in the Immigration Bill:

“Is... the purpose of this change of law, that we might be able to do things that make people vulnerable and deny them their rights, creating yet more black holes where no law obtains but where we cannot be accused of complicity?”

Notably, this was not a question to which the government minister responded. Despite a growing body of evidence demonstrating the UK's involvement in CIA activities ranging from rendition and torture to the covert drone programme, the British government – on the grounds that it must avoid at all costs embarrassing its US ally – has refused to come clean over its role in any of them.

This way of thinking is not limited to parliament – it has also infected the British Courts. Last year, a High Court judge told one of the victims of CIA torture that although he had a “well-founded claim,” he should not be allowed to pursue his case for fear of damaging UK-US relations.

Meanwhile, on the covert drone programme, despite a wave of reports demonstrating that the UK supports it by providing everything from intelligence to crucial infrastructure at US bases on British soil, UK ministers have stonewalled, refusing to go any further than the bland statement that “the use of unmanned aerial vehicles against terrorist targets is a matter for the states involved.”

The picture that emerges from all this is of a Britain which is prepared to take measures that even the US has long determined to be beyond the pale. It is worth returning here to that US Supreme Court ruling mentioned above, which railed against “subject[ing someone] to banishment, a fate universally decried by civilized people,” and making them “stateless, a condition deplored in the international community of democracies.”

Home Secretary Theresa May's measures – which would lift the ban on depriving someone of citizenship, even where doing so would render them stateless – were defeated in the Lords last month. But the government is expected to seek their return in the Commons this week. Aside from putting Britain beyond the “civilized... community of democracies,” in the US Supreme Court's words, they will open up many millions of Britons to the threat of the arbitrary loss of their citizenship, and, potentially, leave them vulnerable to the lawless excesses of the ‘War on Terror’: kidnap or death by drone.

It seems safe to say that the sight of would-be exiles wading into the sea at the Channel ports is not set to return. But the arbitrary nature of these powers, which allow the Home Secretary to act without any legal process and without any crime having been committed, would be all too familiar to the medieval despots of this country’s past.

Donald Campbell is Head of Communications at Reprieve