A council deliberately broke the law by failing to properly assess whether thousands of vulnerable people were illegitimately kept under continuous and restrictive supervision by care home staff, the local government and social care ombudsman has ruled.

Staffordshire contry council decided at an informal cabinet meeting in 2016 that budget cuts meant it would no longer formally consider all requests from care homes and hospitals to place particular residents under tight staff controls.

The assessments – known as deprivation of liberty safeguards (Dols) – are required to provide legal protection for individuals, such as those with dementia or those subject to physical or chemical restraint, who lack capacity to consent to their care or treatment, and to protect them from harm.

The council decided to create its own unofficial guidance to rank requests from care homes under Dols so that it could prioritise a handful of assessments it considered to be the most urgent, while leaving other requests for long periods or entirely ignoring them.

The ombudsman said that in June 2018 the council had a backlog of more than 3,000 Dols requests for which it had not carried out an assessment, with one un-assessed case dating to August 2014. Since May 2016, nearly 2,000 applications had closed without assessment because the person died before it could take place.

This caused a potential injustice to thousands of people who were denied a proper legal access to ensure their deprivation of liberty was lawful, properly made, and implemented only as long as was necessary, the Ombudsman said.

Although in most cases a formal assessment would not have changed the outcome – other than confirming that it was in their best interests to be deprived of liberty – “it is possible some people stuck in the backlog for years should never have been deprived of their liberty,” the ombudsman says.

Michael King, the local government and social care ombudsman, said that although Staffordshire’s practice was “at the extreme end” of the scale nationally, he urged other councils to review their assessment process.

He added: “Resource constraints can never be a legitimate reason for not carrying out the assessments required by law or statutory guidance. While councils may decide how to prioritise cases, it is not acceptable that the only way low- and medium-priority applications are resolved is because the people involved move away or die.”

However, Staffordshire defended its decision to breach the law and guidelines on the grounds that its triage system worked well, that if a person was deprived of liberty they would be compensated, and that thus far “no individual has complained”.

Alan White, Staffordshire’s deputy leader, said: “No one’s life or health has been put at risk because of the assessment policy. The subject of Dols applications are often elderly dementia sufferers, some of whom are in hospices.”

The council said it would cost £3.5m to clear the assessment backlog and this would be unjustifiable because the law is set to change next year, passing the Dols assessments to care homes.

The ombudsman emphasised that the council was still required to follow the current law, which remained the main legal protection available to vulnerable people deprived of their liberty in care homes.

Councils have struggled to keep abreast of a huge increase in Dols requests since a landmark high court ruling in 2014, which in effect decided that all cases must be assessed, even if the person affected did not object. Numbers of requests rose from 13,000 in England in 2013-14 to 227,000 in 2017-18.

A Department of Health and Social Care spokesperson said: “It’s unacceptable for vulnerable people to be left without legal protection, and we expect councils to comply with the law and carry out all necessary assessments. To support them we have given them access to up to £3.6bn more dedicated funding for adult social care this year and up to £3.9bn for next year.

“We recognise the current system for protecting vulnerable people’s freedom needs reforming, and our mental capacity (amendment) bill will reduce how long vulnerable people will have to wait for access to essential protections by simplifying the process, without compromising essential safeguards.”