Senate and House Democrats launched a congressional inquiry on Wednesday into a new controversial Justice Department legal opinion that would make it easier for states to keep people with mental illness institutionalized, rather than paying for them to receive community-based care.

In a letter to Acting Deputy Attorney General Todd Blanche, the lawmakers asked the Justice Department to rescind the June opinion by the Office of Legal Counsel, and asked who was involved in drafting it, in addition to its author, Principal Deputy Assistant Attorney General Lanora Pettit.

“For more than 50 years, federal civil rights laws have recognized that unnecessary segregation and institutionalization constitute discrimination,” they wrote to Blanche. 

“The consequences of weakening the integration mandate would be profound,” they continued. “Millions of Americans with disabilities rely on home and community-based services supporting them to be among their families, maintain employment, pursue education, and participate in civic life.”

The letter was signed by 100 Democratic members of the Senate and House, among them, Sens. Dick Durbin, Tammy Duckworth, Bernie Sanders, Ron Wyden, Chuck Schumer, Sheldon Whitehouse, Elizabeth Warren and Chris Van Hollen. Democratic Reps. Mary Gay Scanlon, Debbie Dingell and Lateefah Simon also signed the letter.

The Office of Legal Counsel in June released a highly controversial legal opinion that civil rights experts told CBS News runs counter to longstanding legal precedent and would lead to greater rates of institutionalizing people with disabilities.

The OLC found that states are not actually required by law to integrate mentally disabled patients with their peers by providing community or home-based care.

The opinion effectively reinterprets a long-standing Supreme Court case that has served as a cornerstone of America’s disability rights law. That 1999 case, Olmstead v. L.C., held that people with disabilities are entitled to receive services in their communities, rather than in an institution.

The Olmstead case was brought by two women with mental and intellectual disabilities who were each repeatedly placed in institutions in Georgia because they could not obtain coverage for the support they needed to live independently at home.

Although the OLC opinion is not legally binding and does not create precedent, it could still be used by federal agencies such as the Justice Department and the Department of Health and Human Services to guide how they enforce allegations of discrimination by patients who received state-funded care.

Bloomberg Law reported that the OLC’s legal opinion was largely driven by White House adviser Stephen Miller, who had expressed frustration over the settlements the Civil Rights Division had reached which compelled states to release people with mental illnesses from institutions. According to the report, Miller felt that these settlements would increase homelessness.

The White House and Justice Department, however, each denied to Bloomberg that Miller had played any role in the memo.

As recently as December, the Justice Department was addressing state violations of the Olmstead ruling. 

“The Department and South Carolina are working together to ensure that people with serious mental illnesses can be served in the community when they want to be,” Assistant Attorney General Harmeet Dhillon said in a news release announcing a settlement with South Carolina late last year. 

In their letter, the Democratic lawmakers asked the Justice Department to “[i]dentify all department officials, political appointees, and outside individuals, including from the White House, who participated in initiating, drafting, reviewing, approving, or advising on the opinion.”

They also asked whether outside companies or groups, including some who advocate for criminalizing homeless people, provided any legal analysis or briefing materials that were reviewed by OLC in connection with the memo.

The Justice Department confirmed it received the letter and said it is “ensuring the appropriate personnel within the Department are reviewing it carefully.”

Because Democrats do not control the Senate or the House, they may only request the information — they cannot require a response under congressional subpoena from the Justice Department.