The findings are based on research published on Wednesday for the Family Justice Council (FJC). It was led by Professor Jane Ireland, a forensic psychologist at the University of Central Lancashire.
Prof Ireland and her team were given unprecedented access to psychologists' expert witness reports from three undisclosed courts across England by the FJC, an arm's length body of the Ministry of Justice.
Experts play a critical role in family court cases: research suggests that at least one expert is used in 90 per cent of public law children's proceedings and many cases involve three or more experts.
The majority of these experts are psychiatrists and psychologists, employed to provide expert opinion on a range of matters in these cases, typically including questions as to whether parents have the ability to care for their children, display personality disorders or other psychological issues and whether any such diagnoses are treatable within a timescale suitable for the children involved.
Channel 4 News spoke to families across the country involved in court proceedings and heard time and again concerns about the experts used by the courts to determine whether children are at risk and should be removed from their birth parents.
But because of the secrecy of the family courts - designed to protect the identity of the children at the heart of proceedings - the experts used have largely been beyond scrutiny.
This research is the first time these concerns have been to some degree independently substantiated. The research found serious concerns across a range of issues beyond the startling finding that around a fifth of so-called psychologist expert witnesses are not qualified.
The assessments of the expert reports found that some 20 per cent of the psychologists were working beyond their area of knowledge; around a third had no experience of mental health assessments; and some 90 per cent of experts were not in current practice.
The net result was that the research concluded that around 65 per cent of expert reports in the study were of either 'poor' or 'very poor' quality.
Professor Ireland told Channel 4 News: "I think we were very concerned and perturbed by some of the reports that we read, not just in terms of qualification but also the quality of the reports that we read ..."
Nigel Priestley, a lawyer closely involved in family proceedings, told Channel 4 News of the gravity of the research's findings. "After the death penalty the most draconian act that the state can do is remove a family's child," he said. "What is at stake for many carers is the loss of their children and on the basis of a report which might or indeed might not be questionable."
He regularly deals with cases where parents feel the expert evidence is flawed. But it is the scale of the problem revealed by the new research which has surprised him.
He said: "If the statistics are that 20 per cent are unqualified that is not just a mess, that is staggering, wrong ... this is not just about making money, this is about removing children very often or, more importantly, protecting children ..."
One of the more surprising findings of the research was that some psychologists were recorded as assessing parents without ever meeting or seeing them.
Prof Ireland told Channel 4 News: "You should never be in a position where you diagnose somebody, or make judgements on them, if you haven't seen them. It goes completely against code of conduct and ethics and it is impossible. You can’t do a paper assessment on a human being, you have to meet that person, understand their interactions, build a rapport and then take your judgement on the basis of that."
But Channel 4 News has learnt that this is not just a problem confined to psychologists. One mother who spoke on condition of anonymity recently left England after a private law family court case over custody of her children.
This case involved some eight expert witnesses. One, a psychiatrist, provided the court with an assessment of a potential change of residence for the children without meeting the mother or the children. The mother described the family court system and the repeated use of experts as barbaric.
The day after the psychiatrist completed the report on the mother he was suspended by the GMC for a separate offence. Yet, despite the concerns over assessing people without ever actually seeing them, it seems that courts are willing to accept such reports.
The research is the first of its kind and clearly has limitations, which the report itself acknowledges. The sample size was relatively small at 126 reports and the methodology to objectively quantify quality is likely to need further refinement.
But the range and scale of the problems identified suggest that this is unlikely to be explained solely by methodological shortcomings.
Intriguingly, the research also suggests that the problems may extend well beyond psychologists. Indeed, in the course of the investigation, Channel 4 News uncovered serious areas of concern with both psychiatrists and paediatricians as well as play therapists and others providing expert services to the family courts.
"I think the results from the research are enough to suggest that we do need an urgent review across the range of expert witnesses that the courts are employing," said Professor Ireland.