The Government has agreed to act after the High Court outlawed a Home Office policy of treating 17-year-olds held in police custody as adults - denying them protections enjoyed by those aged 16 and under.
Two judges declared the policy, contained in a police code of conduct, unlawful and ordered Home Secretary Theresa May to revise it.
The ruling follows the high-profile deaths of two 17-year-olds who killed themselves after getting into trouble with police.
The judges targeted Code C of the Code of Practice under the Police and Criminal Evidence Act 1984, which currently permits the police to treat 17-year-olds as adults.
Code C does not allow them to be treated like those aged 16 and under and contact their parents or seek the advice and assistance of an independent "appropriate" adult - measures their parents say could have saved their lives.
In a landmark decision, two judges declared that the current version of Code C was "unlawful in that it fails to distinguish between 17-year-olds and adults". Lord Justice Moses and Mr Justice Kenneth Parker, sitting at London's High Court, ruled that the flawed code "fails to treat children's best interests as a primary consideration".
The failure breached Article 8 (right to private and family life) of the European Convention on Human Rights as interpreted in light of the UN Convention on the Rights of the Child, said the judges.
They added that Mrs May's failure to revise the code to distinguish between 17-year-olds and adults was "a breach of her obligation under Section 6 of the Human Rights Act 1998 and unlawful". The judges ordered the Home Secretary to now "reconsider and consult" and to lay before Parliament a draft of an order revising the code.
A Home Office spokesman said: "The Government believes the welfare and protection of all those held in police custody, especially young people, is extremely important. We accept the court's judgment and will consider the next steps we should take to implement the changes."
But campaigners pressed the Government to take immediate action and instruct the police to ensure that 17-year-olds in custody have access to parents and appropriate adults, before any more lose their lives.