Milwaukee's sheriff does not have to release information on people at his jail suspected of being in the country illegally because the federal government prohibits it, the Wisconsin Supreme Court ruled Friday.

The 4-2 decision from the court's conservative majority reverses lower-court decisions that ordered Milwaukee County Sheriff David Clarke to disclose the information under the state's open records law, following a request from an immigrant advocacy group.

The ruling is a victory for Milwaukee's sheriff, who has pledged to follow President Donald Trump's directive to crack down on illegal immigration and expand the number of people prioritized for deportation.

Milwaukee-based Voces de La Frontera filed the request in February 2015, asking for records identifying who the sheriff had held at the request of immigration authorities for the prior two months. The group said it wanted to know who the sheriff was detaining and whether they had a criminal record to meet the narrower guidelines former President Barack Obama previously set for deportation.

The immigrant advocacy said it also wanted to monitor whether any U.S. Citizens were being mistakenly detained because they're aware of one case where that happened.