A federal judge has ruled that the Trump administration may soon begin sharing specific Medicaid information concerning suspected undocumented immigrants with Immigration and Customs Enforcement (ICE).

In a decisive seven-page ruling issued on Monday, U.S. District Judge Vince Chhabria determined that sharing details such as “citizenship and immigration status, address, phone number, date of birth, and Medicaid ID” is “clearly authorized by law.” The Department of Homeland Security (DHS) and Department of Health and Human Services (HHS) successfully clarified to the court their reasons for deviating from previous policies that avoided using Medicaid data for immigration enforcement.

The agencies justified their actions by referring to multiple executive orders from President Donald Trump, which directed them to enforce immigration laws and “secure our borders.”

This ruling marks a significant win for the administration’s efforts. Starting January 6, DHS and HHS can collaborate with ICE to share data on suspected undocumented immigrants benefiting from public health insurance, thus providing a new tool for immigration enforcement. However, the scope of information they can share is specifically limited.

Judge Chhabria, appointed by Barack Obama, delivered this decision in response to a preliminary injunction motion from California Attorney General Rob Bonta, representing his state and 21 others, seeking to halt the further dissemination of data. Chhabria sided with Bonta, granting the injunction.

Bonta and the coalition of states initiated a lawsuit on July 1, challenging the Centers for Medicare & Medicaid Services (CMS) under HHS for transferring “a trove of individuals’ protected health data” to federal agencies, including DHS, without consent. Judge Chhabria has temporarily prohibited the administration from sharing Medicaid data “obtained from the plaintiff states for immigration enforcement purposes” until the case is resolved and the agencies provide further explanation.

The judge determined the Trump administration may not share information beyond “basic biographical, location, and contact” because the federal government’s “new policies are totally unclear about what that information would be, why it would be needed for immigration enforcement purposes, and what the risks of sharing it with DHS would be.”

Such reasoning would rule out the government acting “arbitrarily” in violation of the Administrative Procedure Act, the statute governing federal agencies’ behavior. And so while Chhabria opined in the recent order that DHS and HHS adequately explained their actions, allowing for the sharing of certain data, he also found that significant questions remain.

The judge wrote, at length:

Beyond the basic information discussed above, the policies are totally unclear and do not appear to be the product of a coherent decisionmaking process. It is unclear (1) whether DHS may obtain from HHS any information relevant to any proceedings beyond criminal immigration investigations or civil enforcement actions; (2) what data DHS is authorized to obtain from HHS on a “case-by-case” basis and what factors are considered in such inquiries; and (3) whether DHS may request any data from HHS about citizens or lawful permanent residents, including members of mixed-status households. It’s even an open question whether the policies would allow HHS to share sensitive medical information about Medicaid patients with DHS— information that’s difficult to imagine the agency needing for any legitimate purpose. Furthermore, neither the ICE Memo nor the CMS Notice address why a more narrowly tailored policy, focused on the basic biographical information discussed above, would not suffice for immigration enforcement purposes.

Chhabria’s order consequently narrowed the Medicaid information that the administration can share.

“To the extent that such basic biographical, contact, or location information about unlawfully present aliens is not severable from other information that DHS and ICE are not entitled to obtain (e.g., information about lawful permanent residents or citizens, sensitive health records), HHS or CMS may not share it,” he wrote. If DHS requests that additional information be made available to them, they must approach the court.

A spokesperson for the California Department of Justice told Politico after the ruling that individuals signed up for the state’s health care program under the belief their personal information would be used solely for their health care.

“The Trump Administration’s effort to use Medicaid data for immigration enforcement is a violation of their trust and will lead to fewer people seeking vital healthcare,” the agency said in a statement.

DHS spokesperson Tricia McLaughlin, on the other hand, called the court ruling “a victory for the rule of law and American taxpayers.”