There are "large scale" problems in the regime governing the disclosure of criminal records in England and Wales, a government-ordered report has found.
Some people may be being wrongly ruled out of jobs while others who should be excluded may be "slipping through the net", ministers were warned.
The Law Commission described the law surrounding the system as "unclear and confusing" and said there was a "compelling case" for a wider review.
Under the Rehabilitation of Offenders Act 1974, individuals are not required to divulge past convictions and cautions once they have become "spent" - meaning a certain period of time has passed.
But there are some circumstances when disclosure can be requested, and employers are required to carry out checks when hiring people for certain roles such as work with children or vulnerable adults.
The Law Commission was asked by the Home Office last year to examine the effectiveness of a specific aspect of the system known as "filtering".
This is the framework which regulates when someone has to disclose convictions and cautions even though they are spent.
The scheme was introduced so that an individual who would otherwise be required to disclose all of his or her criminal offending history would not be required to do so if the convictions were for old and minor offences.
Inaccuracies in an operational list of "non-filterable" offences - crimes that always have to be revealed - mean some convictions and cautions "could well be wrongly disclosed or wrongly withheld", according to the report.
As well as making a number of findings on filtering, it said: "Given the vast array and magnitude of the problems identified by our provisional assessment of the disclosure system as a whole, there is a compelling case to be made in favour of a wider review."
The present system raises "significant concerns" in relation to non-compliance with the European Convention on Human Rights and "the overly harsh outcomes stemming from a failure to incorporate either proportionality or relevance into disclosure decisions", the study said.
It added: "An impenetrable legislative framework and questions of legal certainty further compound the situation.
"This is an area of law in dire need of thorough and expert analysis.
"A mere technical fix is not sufficient to tackle such interwoven and large scale problems."
A statutory instrument should set out a single, itemised list of non-filterable offences, the report recommended.
It suggested that a rule that convictions were never filtered if there was more than one could be relaxed, while a requirement to disclose all convictions resulting in a custodial sentence might also need to be reconsidered.
Law Commissioner Professor David Ormerod QC said: "Making sure children and vulnerable adults are safe is the number one priority.
"But it's not fair that some people may be being wrongly ruled out of jobs, whilst others who should be excluded could be slipping through the net.
"Government has referred this important work to us and we have made recommendations on how the current process may be simplified, as well as noting the compelling case for a broader review of the whole system."
Most criminal record disclosures are made through the Disclosure and Barring Service system.
In 2015, the DBS processed 4.2 million applications, according to the report.
When filtering rules were applied, the number of certificates issued containing "relevant matters" was 244,000.
A Home Office spokeswoman said: "Offences that are considered to hold a safeguarding risk should always appear on a DBS certificate and the protection of children and vulnerable people is of paramount importance to the Government.
"We asked the Law Commission to undertake this review to ensure the system remains effective.
"We have reviewed their findings and have not identified any violent or sexual offences that have slipped through the net and been omitted from DBS certificates."