The American Civil Liberties Union (ACLU) filed suit against the Missouri Department of Corrections (DOC) this week over allegations that the state is not properly providing hepatitis C virus (HCV) treatment to its inmates, U.S. News & World Report reports.

According to the lawsuit, only 15 of the 4,590 Missouri inmates who have been diagnosed with the virus have had their treatment authorized this year. In response, the ACLU filed a motion on Monday seeking an emergency court order that will force the Missouri DOC and its medical provider, Corizon LLC, to begin testing and treating inmates with the virus.

The motion is the latest move in a related class-action case alleging that state prison officials and Corizon are knowingly and systematically denying lifesaving medications to inmates in order to save money. Around 10% to 15% of Missouri’s 28,000 inmates are thought to be living with the virus—and treatment costs up to $20,000 per patient.

It’s estimated that about 97% of inmates nationwide living with hepatitis C are not getting treated. Advocates argue that under the U.S. Constitution’s Eighth Amendment, they are eligible to receive treatment just like the rest of the general population, regardless of the cost. Refusing to do so, groups like the ACLU argue, is tantamount to “cruel and unusual punishment” under the law.

If successful, the class-action lawsuit could potentially bring hepatitis C treatment to thousands of inmates. Similar lawsuits filed against prison systems in Florida, North Carolina, Colorado and others have successfully secured unconditional treatment for prisoners.

To learn more about hepatitis C in prisons, click here.