When I arrived in Britain to live in 1980, the IRA was in full flight and Bobby Sands was soon to start the hunger strike that would lead to the death of 10 republican prisoners. The Brighton bomb followed a few years later. A tough time you might think to be Irish in Britain – and yet the feelings of alienation, of separateness that follow the Brexit vote are in some ways stronger. After all, the problem in the 1970s and 1980s was that Britain wanted too badly to keep the (Northern) Irish, while now it is that they want rid of the foreigner, or at least the European foreigner – and these days this is what we Irish proudly are, no longer colonial cast-offs pleased to make do with our common travel area but members of the Continental family.

Too many voters thought Leave was about getting rid of people rather than departing a regional organisation for the hostility inherent in the result to be glossed away or explained in other terms. If we thought otherwise the new prime minister’s decision to turn European (including Irish) residents in the UK into bargaining chips in the forthcoming Brexit negotiations would have put us straight: our humanity comes second to our instrumental usefulness.

Standing in the way of the Brexit government remains one slight, much maligned piece of legislation, dating from 1998, the Human Rights Act. This early piece of legislation from the Blair government takes the quaint (but in our present times inconvenient) line that nationality does not determine a person’s human rights, that entitlements to privacy, to family life, to liberty and so on should be enjoyed without discrimination on the basis of any status including – specifically referred to – our “national origin”.

The Act incorporates into UK law the European Convention on Human Rights, an international instrument quite separate from the EU, which through its European Court of Human Rights (based in Strasbourg) has long been vital in curbing the tendency of the UK authorities to violate rights in the pursuit of security-oriented policy goals, not least in Northern Ireland: extended detention; inhumane interrogation; denials of access to lawyers when in custody; and (as the Gibraltar case from the 1990s reminds us) “shoot-to-kill” decisions by British forces.

Theresa May’s government plans to remain within this Convention system but drop its domestic mirror, so ensuring the UK courts cannot directly enforce it. Long a Conservative policy, and figuring among its manifesto pledges in the run-up to the 2015 election, the intention to repeal the Human Rights Act has been confirmed post-Brexit by the new secretary of state for justice, Liz Truss. It can only be a matter of time before this Brexit 2 campaign begins – with the Human Rights Act gone who can doubt that the Convention will be the next to go. If foreigners are merely to be tolerated for their use (and only while this use lasts) and not celebrated for their lived human experiences, of course no laws demanding equality with the British can be allowed to survive.

This is what makes the forthcoming battle over the Human Rights Act so important – it will be about the soul of the UK and will be fought over in parliament, not via a referendum dominated by xenophobes and opportunist populists.

So far the arguments against the Act have been driven by a series of misconceptions about its impact that will need to be exposed if the effort to repeal is to be successfully resisted.

First contrary to what its opponents assert the Human Rights Act respects parliamentary sovereignty. This is made clear throughout the Act. The UK’s elected representatives can do whatever rights-violating that they judge to be necessary. Public authorities must execute such wishes, being specifically protected from being successfully sued under the Human Rights Act whenever they can point to a clear mandate from Parliament to do what they are doing.

The drafters of the Human Rights Act protected parliamentary sovereignty because the Labour government behind the measure insisted on it. As a consolation to rights-supporters more fervent than themselves, the law also included a special pseudo-remedy where parliament has acted in a direct, rights-infringing way, “the declaration of incompatibility”. This allows the UK’s top courts to declare a law “incompatible” with the rights in the Human Rights Act but specifically states that such “declarations” are to carry no legal impact whatsoever. Breaching human rights remains something of which politicians are not proud, so those declarations that the courts have made have generally been followed up by the government. But crucially they have not needed to be.

Second, and once again contrary to the noisy declamations of the Europhobes, the European Court of Human Rights does not rule over the UK courts. The Human Rights Act makes clear that the UK courts must know about the Strasbourg case-law relevant to the case before them whilst also making explicit that they do not have to “follow” it in the slavish way lower courts do to decisions in the British system further up the pecking order (the doctrine of precedent). After a false start – when the judges here were a bit too over-enthusiastic in following Strasbourg – the position is now clear that this bit of the Act means what it says: that the judges can depart from Strasbourg where they feel strongly that that court has got it wrong, as has happened on for example the laws of evidence in serious criminal trials and the rules on life imprisonment.

Thirdly, the most important, least-regarded truth of all, the Human Rights Act is no charter for villains but rather protects everyone. The Act is the reason why there is in the UK now some protection from the intrusion of the media into private lives. If resident in a care home, it is because of the Act that one has a better chance of being treated with dignity and respect. It is because of the Act that public authorities need now to be more careful how they respond to plausible death threats by strangers against those they stalk, and why housing authorities need to be more open to discussion before they make eviction decisions. If one joins the armed forces, it is because of the fear of accountability under the Human Rights Act that army chiefs need to be careful before they send someone to their deaths in undefended transport vehicles at war or into murderously savage training routines at peace. If those whom we care about die in unexpected ways the Human Rights Act gives us a fighting chance of finding out what really happened, as in Hillsborough or domestic violence or in cases of failure of child protection. Of course the Human Rights Act has also insisted on protections for prisoners, suspected terrorists, asylum seekers and others who are traditionally unable to rely on the law for support. This should be reason enough to argue for its retention. But the Act goes much further than that too, reaching everyone. We are all only one unlucky or ill-judged step away from needing the Act.

Quite apart from these basic, under-reported truths, and as is well-known in Ireland, there are the hugely important national questions. The Labour government that enacted the Human Rights Act embedded it in the devolution arrangements that were achieved in Scotland, Wales and Northern Ireland in the same year as the measure’s enactment. Each model is different but they share a commitment to human rights as a central theme. Of the three, only Wales voted Brexit with England – the other two were solid remainers. For Westminster now to impose repeal of the Act would be like throwing further petrol on the raging fire of alienation that Brexit has already started.

In the Republic we have also incorporated the European Convention into our domestic law as a direct result of the obligations we took on as part of the peace settlement, something to which the British would now seem indifferent. Respect for human rights was one of the issues intelligently deployed by Republican leaders in Northern Ireland in the late 1990s to camouflage their submission on the national question. But are the UK authorities now casually to strip that victory from them? A conversation about reopening the Irish unity issue has already begun in Ireland post-Brexit. If the Human Rights Act were now to be undone, might space be being unwittingly created for further reneging on past promises by darker forces?

The so-called British bill of rights that is being proposed as a replacement is merely a cover with which to disguise the sharp reduction in rights protection that repeal of the Human Rights Act would necessarily entail. The headline claims will no doubt be loud, but the small print devastating for the principles of universality, justice and fairness that are what the Human Rights Act is all about. The idea of a British bill of rights imposed by parliament on the whole kingdom is of a piece with the fantasy that drove Brexit – a lost vision of a homogenous, Westminster-led land in which everyone knew their place. We should celebrate the departure of this vision not legislate to fool ourselves into believing it continues.

Conor Gearty is Professor of Human Rights Law, London School of Economics and the author of On Fantasy Island. Britain, Strasbourg and Human Rights (Oxford University Press)