Article 39 is questioning the effectiveness of independent reviewing officers (IROs) who should scrutinise and challenge the need for the placement before a child is moved.
The charity has submitted a request to children and family court advisory and support service Cafcass, under the Freedom of Information Act, to "ascertain how well the IRO/Cafcass legal safety net is working for children".
Article 39's actions follow a BBC Newsnight investigation, broadcast last month, which reported that the number of looked after children aged 16 and over living in unregulated accommodation rose by 70 per cent in a decade.
The programme highlighted concerns that children in some settings are being exploited by gangs through a lack of effective care and safeguarding.
The homes are not registered or inspected by Ofsted and meanwhile police have raised concerns that they provide an easy target for gangs looking to recruit vulnerable teenagers.
Carolyne Willow, Article 39's director, described the situation as a "care paradox", in which children are placed by social workers "in accommodation operating outside the law".
Willow is calling for better safeguards and claimed that the "contorted legal arrangements for placing children in unregulated accommodation show successive governments are aware of the risks and the dangers".
"Teenagers' growing independence is not a legitimate reason for relaxing safeguards," she said.
"If a child is in care, they must be properly cared for - in settings which are registered, inspected and meet minimum standards.
"Councils are at breaking point with lack of resources but these are children for whom councils are legally serving the function of parents and families.
"It can never be right for a child in the care of the state to be placed in a setting where they are abused and exploited, or in which they simply cannot possibly feel loved or looked after.
"We support wider calls for a comprehensive review of the care system, conducted with care experienced people of all ages, to eliminate this and other practices which clearly work against what's best for children. Meanwhile, intervention by independent reviewing officers will be essential for children not in safe or suitable accommodation today."
Commenting previously on the issue, the Association of Directors of Children's Services (ADCS) acknowledged that unregulated provision plays a role "within the care placement market" and that it offers flexibility "when linked to a clear plan based on the needs of a young person and a clear support plan".
The ADCS added: "There is a distinction to be made between using it as part of a considered move compared with using it to deal with a crisis when no other accommodation is available.
"Total regulation would limit this flexibility so we are keen to see all providers take their responsibilities seriously and welcome increased expectations around standards and transparency as to how those will be delivered."
The Department of Health and Social Care has been approached for comment.