The family of a woman who died after taking an overdose of diet pills is applying for a judicial review to overturn a coroner's conclusion of suicide.
Bethany Shipsey, 21, from Worcester, died after taking tablets containing the substance DNP in February 2017.
At an inquest in January, senior coroner Geraint Williams gave a narrative conclusion on her death, but said she intended to take her own life.
He has been approached for comment.
Doug and Carole Shipsey are arguing the ruling is unlawful, claiming the coroner failed to apply the correct legal test for a suicide conclusion, which required him to be sure "beyond reasonable doubt" their daughter intended to take her own life.
Miss Shipsey suffered from borderline personality disorder (BPD), which she developed after she was raped, and had previously taken 14 overdoses.
At her inquest at Worcestershire Coroners Court, the coroner said there were "significant failings" in the care she received at Worcestershire Royal Hospital on the night of her death, but said he believed Miss Shipsey "deliberately ingested" the pills.
Her family believe evidence given by her mother and psychiatrist, and messages she sent to friends, show the overdose may have been a "cry for help".
They have instructed solicitors Irwin Mitchell to apply for the judicial review and launched a crowdfunding appeal to pay for it.
Mr Shipsey, 52, said they hope that the challenge can ensure the inquest "is a fair reflection of how Beth died".
"There is a huge amount of evidence that we feel the coroner failed to take into account," he added.