An Aboriginal man has died in custody in Western Australia.

The 51-year-old was taken from Hakea Prison to Fiona Stanley Hospital on 1 February for treatment following a medical episode.

On Tuesday the WA Department of Justice announced the man died on Monday morning.

WA Police will prepare a report for the State Coroner, as is mandatory in all cases of deaths in custody.

Almost 600 Indigenous people have died in custody across Australia since the Royal Commission into Aboriginal Deaths in custody made its recommendations in 1991.

Noongar human rights law expert Dr Hannah McGlade told National Indigenous Times the case represented "another Aboriginal life taken too soon by the state, and a criminal justice system that is discriminatory and abusive".

"Clearly there are systemic failures in the prison health system," she said.

"Noongar father Wayne Ugle was only 41 when he died at Hakea prison last November, begging for his medication. His family have no answers, other than knowing that racism killed their beloved father and husband.

"Too many Aboriginal people are being incarcerated here and nationally, many are on remand and haven't even been convicted."

Dr McGlade noted that the Royal Commission into Aboriginal Deaths in Custody, and the ALRC Inquiry Pathways to Justice have made clear recommendations to governments.

"The ACT has taken the right step to review their criminal laws and impacts on Aboriginal people. The AG Mr (John) Quigley should stand true to his word of being concerned about Aboriginal incarceration and follow ACT's leadership. The states inaction is unacceptable and clearly costing the lives of our people."