More than one in two people with illness or disabilities who took the government to court after losing out on benefits went on to win their case.
Analysis of Freedom of Information responses shows 65,750 people in Scotland were wrongly denied disability benefits from 2013 to 2018.
Charities and advice providers said the figures show the government’s benefits tests were beset by “poor decision-making” and “obvious inaccuracies”.
Most of the appeals concerned Employment Support Allowance (ESA), which is paid to people who cannot work because of illness or disability; the Disability Living Allowance (DLA), which is paid to people with extra care or mobility needs; and Personal Independence Payments (PIP), which was introduced to replace DLA.
Daphne Hall, the vice chair of the National Association of Welfare Rights Advisers, said: “The reason for the high success rates [at tribunals] is because of the poor assessments carried out by health professionals.
“The DWP tend to base their decision purely on these assessments and disregard other evidence sent in by the claimant.”
Initial assessments are carried out on behalf of the Department for Work and Pensions (DWP) by the private companies Capita and the Independent Assessment Services (formerly called Atos), which have come under criticism for scoring claimants too harshly.
In 2017, Britain’s most senior tribunal judge, Sir Ernest Ryder, senior president of tribunals, said the quality of evidence provided by the DWP was so poor it would be “wholly inadmissible” in any other court.
Capita and Maximus said the majority of people were satisfied with the process, and they were working with charities and disabled people’s organisations to improve their services further.
The government says appeals represent a small percentage of all benefits claim it handles.
The success rate for disability, sickness and incapacity benefits appeals has risen from 44 per cent to 65 per cent over the five-year period
Overall, some 121,312 people who had lost disability, sickness and incapacity benefits appealed against their decision at tribunal, with 65,750 succeeding.
When all types of benefits are considered, the success rate rose from 41 per cent in 2013-14 to 63 per cent in the period from April 2018-December 2018, with some 71,020 people successful over the period.
Between 2013-14 and 2014-15, there was a 76 per cent drop in the number of appeals against all types of benefits which were decided. Since 2014-15, the number of benefits appeals cleared at hearings has risen each year.
Experts say the initial reduction was down to the introduction of written reviews, so-called mandatory reconsiderations.
This is the first stage of the appeal process when claimants ask the DWP to look at the decision again.
Cuts to legal aid were partly responsible for the drop in appeals, charities said.
Prior to 2013, lawyers could receive funding for legal help including advice, assistance and casework.
In 2010, the government said it would reform the “complex, outdated and wildly expensive system” of multiple types of benefits, to cut long-term welfare dependency and fraud.
Then-Work and Pensions Secretary Iain Duncan Smith said those who were “genuinely sick, disabled or were retired... had nothing to fear”.
About three-quarters of working-age benefits are spent in one of three ways:
• Universal credit or tax credits, mostly topping up the incomes of families with someone in paid work, but on modest earnings;
• Housing benefit, helping low-income people meet the cost of rent;
• Disability, incapacity and sickness benefits, for those whose health limits their ability to work or adds to the cost of living.
Since 2013, people seeking to overturn a benefits ruling must complete a written challenge within a month, known as a mandatory reconsideration.
If unsuccessful, people can appeal against the decision at tribunal.
The DWP says mandatory reconsiderations were introduced to ensure claimants receive the right decision without having to go to court.
Critics say the process is confusing and does not give claimants sufficient time to gather evidence to support their appeal.