The U.S. Supreme Court ruled in the Dept. of Commerce v. New York, where the state of New York sued over the question the Trump administration placed on the census asking about legal citizenship.
The Court decided that they agreed with lower court decisions and that the reason for putting the question on the census was "invalid."
It was a 5-4 ruling but it was Chief Justice John Roberts who joined with the liberal justices.
The Trump administration claimed they needed the question to comply with federal voting rights laws, but New York called it purely partisan because it will prompt fewer Latinos to fill out the census. With fewer people filling out the census, legislative seats are more likely to garner Republican Congressional districts through gerrymandering.
The piece of the argument that made things different was that a key Republican operative who recently died had developed a plan for this census question for exactly this purpose. The hard drives uncovered on the late GOP operative showed that the Trump administration used his documents to justify putting the question on the census.
"The documents released yesterday make clear that the administration’s true motivation for adding the citizenship question is to enable a political power grab that would benefit Republican voters while disenfranchising Democrats and people of color," wrote the Brennan Center for Justice.
Each lower court considering the issue has blocked the Trump administration from adding the question. Congress has attempted to hold a hearing and investigate the issue, but Commerce Secretary Wilbur Ross has refused to appear or provide documents.
The decision sent the question back to lower courts and told the Commerce Department that they could try to write the question again, though it didn't give guidance for how. The Commerce Department said that they had to have the decision by the court by the end of June because they had to print the census out. If the Department rewrites the question and asks the Supreme Court to rule on the re-written question, it would not be decided until the next session, because the court goes on a break until their October term.