Children's rights charity Article 39 wants the "myth busting" guide removed from circulation and has applied for a judicial review of the DfE's decision to publish it.
The news follows a pre-action letter from the charity in January, which demanded the DfE withdraw the guide.
Children's minister Nadhim Zahawi also received a joint letter signed by 50 charities and sector experts in September last year, which set out the claimed legal inaccuracies in the document.
The charity's application has been made by legal firm Simpson Millar, and solicitor Oliver Studdert said: "The ‘myth busting' guide removes important statutory safeguards which were put in place to protect some of the most vulnerable people in society.
"In following this guide, local authorities will be denying fundamental support and protection, set out in law, to large numbers of children and young people in need."
It is challenging what it says are the guide's claims that:
- Social workers do not have to lead assessments of children who automatically gain "looked after" status and protections when remanded to custody
- Councils do not have to offer a return home interview to children who have run away or gone missing
- Councils do not have to appoint separate social workers to foster carers and children in long-term placements
- Personal advisers appointed to advise and support young people leaving care can take on the local authority's duties in respect of "Staying Put" arrangements - where 18- to 21-year-olds can continue living with their foster carers
- Social workers only have to make one visit a year to foster carers looking after a child for more than a year
- Social workers can decide to visit children in long-term foster placements as little as twice a year
Article 39 director, Carolyne Willow, said it was "deeply regrettable" that Zahawi had not withdrawn the document following earlier calls from the organisation.
"This document overwrites key obligations within our children's social care system, which were crafted over many years and subject to detailed public consultations," said Willow.
"The protections the guide presents as mythical exist in our legislation and statutory guidance because of the real needs of real children and young people.
"It shouldn't fall to vulnerable children and young people, many of whom are in the care of the state, to have to go to court to defend the protections parliament and successive governments have given them."
Following Article 39's application lodged on 18 February 2019, a judge will now decide whether to allow permission for judicial review.
The DfE has been approached for a response.
