THE House of Lords began considering the Government's Immigration Bill this week. The Bill will have a devastating impact on some of the most vulnerable people in Britain, and could engulf all of usin its ramifications. It wended its way through the House of Commons largely unchanged, however, except for the addition of an eye-watering new power to make foreign-born Britons stateless.

As political debate on immigration is now paralysed by macho posturing, it is going to take courageous leadership from the Bishops in the House of Lords to get this Bill the clear-headed scrutiny that it so badly needs.

You may have seen some of the headline features in the Bill - new powers to prevent so-called "illegals" from renting property, driving cars, and getting a bank account - but there has been little coverage of what this means in practice, and whom it will affect, while much of the rest of the Bill has had no coverage at all.

There are sweeping powers allowing immigration officers to use force (despite the appalling record they have of using force), and increased powers to remove people from the country without challenge.

People in immigration detention can already face indefinite imprisonment, and yet their rights to seek bail are being curtailed. Those whose application to remain here for work, love, or study is turned down will not now be able to appeal.

There is also the attack on children's rights, and the mess of the health-charging scheme. There is a combined effect of all of this, as people's right to challenge what is being done to them is being systematically dismantled by removing access to legal aid.

PLATITUDES about "fairness" tumble from the lips of government ministers concerning immigration, without reference to any framework of ethical reasoning. But, instead of holding ministers to account, political opponents scrap over the mantle of toughness.

There is much wrong with the immigration system, but this Bill will not fix any of it. It is, instead, a project focused entirely on short-term headlines, which have been announced as the solution to problems that have been poorly defined, at the expense of those who already have little or no agency to argue for themselves.

Take the proposal to prevent those without immigration status from renting property: this is just as likely to affect perfectly legal residents who cannot prove their status to their landlord, as to catch over-stayers - a woman fleeing domestic violence, or a vulnerable migrant with a chaotic history is hardly likely to have the necessary documentation to hand.

Furthermore, immigration status can be contained in any one of dozens of different documents, and, in a competitive rental market, what landlord would wait to investigate such difficult paperwork, when other tenants stand ready to step in? We are in danger of consigning anyone who looks a bit foreign to the grottiest property, if they can rent at all.

Then there is the removal of the right to appeal against an immigration decision. The Government claims that it is getting tough on those who fail to play by the rules and abuse the system. But most of the people who will be affected by this change are those who have played by the rules: people who came here to work or study, and applied for an extension of their right to go on doing so. Worse, the Bill attempts to rewrite what constitutes a right to private and family life in ways that make children largely invisible (including when the case concerns children themselves).

Similarly, the NHS charges are marketed as the end of "health tourism". But those who will be caught by the charges are those who have been here for many years on a work visa and are paying taxes. It will affect the families of refugees who come here for family reunion, unaccompanied child migrants who get leave to remain at 18, and spouses who come here to live with their partner. All this to solve an ill-defined problem that is estimated to cost the NHS about £50 million a year, or 0.01 per cent of the total NHS budget.

THE impact of these policies is in danger of creating a hostile environment for all migrants, with the greatest burden falling on the most vulnerable, and on anxious families, such as those who have fled persecution or violence, who may wait years for a decision on their immigration status.

This is because this is not just a problem of policy detail. It is also about the damaging impact of rhetoric: rhetoric that gets people turned away from health services; rhetoric that makes landlords think twice about renting property; rhetoric that drives wedges between individuals and between communities, making us all that bit poorer, whether we are migrant or native.

All too often, the human stories of those on whom we are getting tough get lost in the tabloid front pages and speeches inspired by opinion polls. But they are often stories of acute distress, stories their protagonists will never tell, and which their subjects have no chance to tell themselves. The Bishops may tell their stories in the coming weeks. I am not sure, otherwise, that anyone else will.

Sarah Teather is the Liberal Democrat MP for Brent Central. She chairs the All-Party Parliamentary Group on Refugees, and is a member of the All-Party Parliamentary Group on Migration.