Disability benefit claimants are now winning record levels of appeals against the Department for Work and Pensions, new figures show.
Assessments for Personal Independence Payment (PIP) and Employment and Support Allowance (ESA) have been branded "a total failure" and "not fit for purpose" in the wake of the Government statistics.
In the past three months, independent tribunals ruled in favour of claimants in 69% of appeal cases for both benefits.
This represents the highest percentage ever for PIP over a three-month period.
DWP says only a fraction of cases are taken to appeal and most decisions are overturned because claimants submit more evidence.
"With 69% of both Personal Independence Payment and Employment and Support Allowance decisions being overturned at appeal, it is clear the assessment process is a total failure and not fit for purpose," said shadow work and pensions secretary Debbie Abrahams.
"We know from the recent Work and Pensions select committee's damning report that these assessments cause unnecessary stress and anxiety for the thousands who have been denied support unfairly, as well as wasting public money by sending so many decisions back to the courts.
"The Government is failing sick and disabled people by knowingly allowing this injustice to continue. The Tories must act on the select committee's recommendations immediately."
PIP helps disabled people meet additional costs they face because of their impairment or condition, whilst ESA provides support for disabled people whilst out of work.
The figures, released by the Ministry of Justice, which manages the tribunal service, show 12,195 of 17,785 of ESA cases taken to appeal went in favour of the claimant between October and December.
For PIP, it was 13,881 of 20,144 cases taken to appeal over the same time frame.
Mark Atkinson, chief executive at disability charity Scope, said: "The Government needs to get a grip on this situation, as both PIP and ESA appeals are still being won at alarmingly high rates.
"Disabled people rely on these financial lifelines to live independently and be part of their community.
"Without urgent action, vast numbers will continue to be denied this support unfairly.
"The assessments for PIP and ESA must be overhauled to iron out the mistrust, lack of transparency and routine inaccuracies which disabled people report on a weekly basis."
Nearly half of claimants that have moved over to PIP from the old Disability Living Allowance system have had their benefit initially downgraded or stopped.
Claimants must go through a so-called mandatory reconsideration, an internal review by DWP, before they can appeal to an independent tribunal.
The MoJ spent £103.1 million on social security and child support tribunals in 2016/17, the vast majority of which were for PIP and ESA.
In addition, DWP has spent £108.1 million on direct staffing costs for ESA and PIP mandatory reconsiderations and appeals since October 2015, according to figures obtained by the Press Association.
Stephen Lloyd, Liberal Democrat work and pensions spokesman, said: "These figures are absolutely appalling, but of little surprise to me.
"With the many constituents who come through my office and those of other MPs across the country, we see with our own eyes some shocking decisions by work capability tribunals.
"It is time that we stop faceless corporations making money off the backs of disabled people, while providing poor quality service."
A DWP spokeswoman said: "We are absolutely committed to ensuring that disabled people get the support they're entitled to.
"Since PIP was introduced more than 2.9 million decisions have been made, and of these 8% have been appealed and 4% have been overturned.
"In the majority of successful appeals, decisions are overturned because people have submitted more evidence."