They claim little has been done to protect inmates or prison staff from catching coronavirus.
French inmates have hit out over hygiene at their jails amid fears they are not being protected against the coronavirus outbreak.
Thirty-one detainees from prisons in the south of the country have filed a complaint criticising "deplorable" conditions.
"No health measures have been put in place except for the suspension of family visiting rooms, to protect both prison staff and detained persons," said their lawyer, Khadija Aoudia, contacted by Euronews.
"For some inmates, their condition has considerably decreased: for example in Tarascon, one of my clients, who suffers from diabetes, no longer has access to insulin because the infirmary is closed. In some other prisons, they are sometimes two to four people sharing the same cell," she deplored.
The complainants denounce in their complaint "deplorable hygiene conditions, inhuman and degrading conditions of detention (...) to which are added prisoners weakened by their physical and psychological health, (...) cells of nine square meters on average, where two to three people are detained ".
They also hit out at unprotected prison officials escorting inmates to court "are all factors facilitating contamination, with potentially fatal outcome for the most vulnerable ones".
"The Minister of Justice did not take the imperative and urgent measures which were necessary to bring assistance and help to the prison administration, when she could not ignore the existence of an immediate and constant danger caused by COVID-19," continued Aoudia.
"Having to take a legal action is unfortunate. But it's necessary for social peace."
The complaint directly targets Justice Minister Nicole Belloubet and Prime Minister Edouard Philippe.
The charge is "failure to assist a person in danger", and the penalty may lead to 5 years' imprisonment - "because we can prove that nothing has been done to prevent this dramatic situation," Aoudia concluded.
It comes after a 74-year-old inmate at Fresnes prison near Paris died of COVID-19 at the beginning of the coronavirus outbreak.
On Thursday morning, Belloubet confirmed on France Inter radio station that ten inmates have contracted COVID-19 and around 450 were "showing some symptoms".
On Wednesday, she moved to try and simplify the release of detainees at the end of their prison terms.
Between 5,000 and 6,000 prisoners could thus benefit from early release, she said.
"On the other hand, I am opposed to a general measure which would aim to release all those who are in pre-trial detention," she added.
According to Aoudia, such measures already existed before Belloubet's decision. The lawyer insisted on the fact that a majority of inmates in pre-trial detention are imprisoned for petty crimes: "Setting free psychopaths is out of the question of course, but we are creating a human bomb [while doing nothing]."
Belloubet announced 116,000 protective masks had been distributed to prisons.
She is also considering "two months of sentence reduction for those who will show an exemplary behaviour during this period".
Belloubet said she was "careful to take all measures" to prevent the epidemic from spreading behind closed doors, particularly in remand centres where cells are often crowded and it is difficult to keep people apart.
Earlier this week, she tweeted that "one of [her] priorities is to fight the spread of COVID-19 in prisons."
She also paid tribute to "justice workers who courageously commit themselves to ensuring the continuity of public service."
French prisons, which suffer from chronic overcrowding, have more than 70,000 prisoners but a capacity for 61,000.