The parents of two teenagers who killed themselves after being arrested have delivered a petition to Downing Street calling for a change in the law.
Under the current system the families of Joe Lawton and Edward Thornber, both 17 and from Greater Manchester, were not informed of their arrests.
A petition calling for the government to treat 17-year-olds as children in custody gathered 53,000 signatures.
The Home Office said existing laws ensure appropriate care in custody.
Nick Lawton said if he been informed of the arrest he could have supported his son.
Nick and Jane Lawton's son Joe committed suicide two days after being arrested for drink-driving after driving home from a party last August.
He had used the shotgun from the family farm and the police charge sheet was at his feet when his father found him.
Adrian and Ann Thornber's son Edward, of Didsbury, was found hanged after being summoned to court when he was caught smoking cannabis.
In both cases the parents were not informed of the arrests because their sons were treated as adults in custody - even though if they were charged they would have been treated as children.
The families are campaigning for the government to address the "anomaly".
According to the Home Office, every year 75,000 17-year-olds are taken into police custody.
Mr Lawton, of Stockport, said that he hoped the "groundswell" of public support would encourage ministers to act.
'Needed family support'
He said: "We don't want other families to go through what we went through. It's dreadful.
"He couldn't find the words to tell us and he needed the support of his family at that very difficult time.
"But we were denied that opportunity to help him because at no time while Joe was in custody were we told of that.
"Very few people are aware of this anomaly in the law - how can you be an adult one moment and a child the next? That simply isn't right."
The families say the law must be changed to protect 17-year-olds under the United Nations Convention on the Rights of the Child.
A judicial review into the issue is ongoing.
Policing minister Damian Green said: "The deaths of Joe Lawton and Edward Thornber were tragedies and our thoughts are with their families.
"The welfare of anyone remanded in custody is considered at every stage of the process. Existing laws ensure a proper level of care is provided with special provisions in place for young and vulnerable people.
"It would be inappropriate to comment further while legal proceedings are ongoing."
Shauneen Lambe, of charity Just For Kids, said: "The Home Secretary can easily make this change.
"I would hope that calls from 50,000 people across the UK and the heartbreaking stories of these two families is enough to tip the balance."