A single mother living in a three-bedroom council house fitted with a secure panic room to protect her from a violent ex-partner is fighting for exemption from the so-called bedroom tax.
The woman, referred to as "A", has taken her test case battle to the High Court.
She is seeking judicial review on the grounds that the Work and Pensions Secretary, Iain Duncan Smith, is infringing both European and domestic law by refusing to exempt her and other women in a similar situation under the housing benefit regulations.
Caoilfhionn Gallagher, a public law specialist barrister, said A, who lives with her 11-year-old son, was "acutely aware of the political sensitivity" of her legal challenge.
Ms Gallagher told Judge Worster, sitting in London, it was an important test case because of the "disproportionate impact" of the regulations on female victims of severe domestic violence in need of a place of refuge in order to remain living in their homes.
The court heard submissions that A's former partner has raped, assaulted and harassed her and threatened to kill her but she nevertheless faces losing £11.65 a week from her benefits.
This is because her panic room is regarded as a spare room under the 2012 regulations and A is deemed to be "under occupying" her home.
The Department for Work and Pensions (DWP) argues her challenge lacks credibility because funds in the form of discretionary housing payments (DHPs) have been made available through local councils to people facing exceptional circumstances.
A DWP spokesman said: "This is exactly why we have made £345 million available to councils to help vulnerable people. We understand the council have awarded a payment to make up a shortfall in rent."
The Government rejects the term "bedroom tax" and says the regulations remove what is in fact a "spare room subsidy".
The aim is to encourage people to move to smaller properties, thus saving around £480m a year from the housing benefit bill.
The panic room case is the latest in a series of High Court challenges to the controversial new regulations.
The judge heard that information obtained under the Freedom of Information Act from 125 local authorities revealed at least 4,366 households involved in sanctuary schemes.
A total of 120 participants in those schemes were affected by the under-occupancy regulations, with an average expected loss of benefits per week of £16.70.
Of those 120, 80% were not receiving DHPs, Ms Gallagher told the High Court.
She argued the regulations breached human rights and equality laws and were discriminatory because they disproportionately affected women, who were mostly the victims of domestic violence.
Sanctuary schemes provide a secure room or space with special safety measures, including reinforced doors and windows, to which a person threatened with violence can retreat whilst they await assistance.
Addresses are "tagged" on police computers to ensure fast responses by the police following a 999 call or a person hitting their panic button.
Rebekah Carrier, the solicitor acting for A, said: "These changes to housing benefit are having a catastrophic impact upon vulnerable people across the country.
"Our client's life is at risk and she is terrified. She lives in a property which has been specially adapted by the police, at great expense, to protect her and her child. It is ridiculous that she is now being told she must move to another property (where she will not have any of these protections) or else take in a lodger."