A mentally ill man who starved to death after his benefits were stopped was left at risk of "serious harm" by the government, the High Court has heard.
Errol Graham's emaciated body was found in June 2018 when bailiffs broke into his Nottingham flat to evict him.
His family believe the Department for Work and Pensions' (DWP) handling of the 57-year-old's case was unlawful and breached his human rights.
Their case is being heard in the High Court.
An inquest into Mr Graham's death heard his benefits were stopped between August and October 2017.
It was told he had a history of depression and missed GP appointments. He refused help from mental health teams and ignored contact from the DWP.
When his body was found, Mr Graham weighed four-and-a-half stone (30kg) and his family said he had used pliers to pull out his teeth.
Before the hearing Alison Turner, fiancée of Mr Graham's son, said she believed the DWP breached equality legislation by not considering whether his mental state was a factor when he missed a fitness for work assessment and ignored phone calls and home visits.
She said while the department's safeguarding policies had been bolstered since Mr Graham's death, they remained unlawful by putting the onus on vulnerable people to prove why appointments had been missed.
"Although, at first, the DWP maintained their safeguarding policy was lawful, faced with a court case, they have made some changes to the policy," she said.
"But these changes are not enough. It still falls to the vulnerable claimant to make sure the DWP knows why they have good cause not to respond to inquiries.
"That makes no sense when vulnerable claimants might be too mentally ill to respond."
At a remote hearing, which began on Tuesday, Ms Turner's barrister Adam Straw told Mr Justice Bourne the claim concerns "a well-recognised cohort of [benefits] claimants who are unable, because of mental disabilities, to engage with, or respond to the DWP".
He said claimants are "frequently unable to respond to or engage with the DWP because of mental disability or illness", with rejected applications presenting "a significant risk to their health".
"It is a momentous decision which will often entail a sudden and complete loss of income - leaving the person destitute without food and housing," he said.
"Withdrawing benefits for a vulnerable claimant like Mr Graham will often put that individual at risk of serious harm."
Mr Straw said Mr Graham had been paid Employment and Support Allowance (ESA) since 2013 due to a long-term illness, which was withdrawn by the DWP in 2017 after the government determined he "had not proved that he had a good cause for not responding" to attempts to contact him.
He said other cases show some claimants are "prevented from responding" due to the nature of their illnesses, adding DWP policy puts "the onus" on proving such conditions affect communication on the claimant.
"In such cases, placing the onus or burden on the claimant to prove why he or she had good cause is contrary to case law and inconsistent with the objectives of the legislation," he said.
"It incorporates an error of law, provides a misleading impression of what the law is and permits or encourages unlawful decision-making."
The hearing is set to finish on Wednesday, with the judge giving his ruling at a later date.