Carlos Ghosn's family lawyer has said the former Nissan boss is being "held hostage" by the Japanese legal system.
Jessica Finelle told the BBC Mr Ghosn's "arbitrary detention" violated his right to a fair trial and says a complaint has been filed with the UN.
She said the standard of his treatment did not meet international norms.
His wife, Carole Ghosn, was also a victim of the "brutal" manner in which his re-arrest was conducted, she added.
Mrs Ghosn said she felt "in danger" and has now returned to France to ask the government there to intervene on her husband's behalf.
The former boss of Nissan was first detained in November, and has since been charged with several transgressions including under-reporting his pay package and transferring Nissan funds for personal use. He has denied all of the charges.
Although he was eventually granted bail, he spent three months in custody.
His lawyer, Ms Finelle, said for some of that time he hadn't had access to his case file or an opportunity to contest his detention – a victim of Japan's "hostage justice system".
"He is basically treated in a way that's he's pressurised – to weaken him so that he will make forced confessions," she said.
She also accused prosecutors of conducting Mr Ghosn's re-arrest last week in a "very brutal" fashion, as if he and his wife were "dangerous terrorists".
She said although Mr Ghosn had adhered to court-imposed bail conditions, the prosecutors office had sent 20 people to arrest him at 05:50 local time on Thursday (20:50 GMT Wednesday).
Mr Ghosn's wife, Carole, was only allowed to shower in the presence of a female police officer and was subjected to a full body search, she said.
They took her passport, mobile phones, and computer, and attempted to interview her without her lawyer being present, Ms Finelle added.
Mrs Ghosn later told media outlets she felt "in danger" and had decided to return to France toRead More – Source