Given the task definition and input, reply with output. Generate an explanation for the given claim using the provided supporting material from the paragraph. Please consider the following points while generating an output. 1) The claim will always have supporting proof in the paragraph, and the paragraph will have a clear point of view supporting the claim. 2) There can be instances where direct correlation to the claim is not available. Make use of the sentences in the paragraph to provide a corresponding output supporting the claim. 3) The explanation should be at least one and at most twelve sentences long.

Paragraph: The American Civil Liberties Union's Rhode Island chapter announced Friday it filed a federal class action lawsuit with Disability Rights Rhode Island and the ACLU's National Prison Project, alleging constitutional violations of the rights of prisoners with serious mental illness. The suit was filed on behalf of inmates. Corrections Department spokesman J.R. Ventura says they've trained staff on best practices and partnered across state agencies to guarantee high-quality mental health care. He says they "strongly dispute" the ACLU's claims. The suit accuses the department of subjecting people with serious and persistent mental illness to prolonged solitary confinement, despite knowing the serious risk of harm these conditions pose. It seeks changes to how inmates are housed. Claim: Lawsuit filed over treatment of inmates with mental illness.
Civil liberties advocates are suing the Rhode Island prisons department over its treatment of inmates with mental illness.