The Supreme Court agreed Friday to take up President Donald Trump’s policy, blocked by a lower court, to exclude people living in the U.S. illegally from the census count that will be used to allocate seats in the House of Representatives. Never in U.S. history have immigrants been excluded from the population count that determines how House seats, and by extension Electoral College votes, are divided among the states, a three-judge federal count said in September when it held Trump’s policy illegal.

The justices put the case on a fast track, setting arguments for Nov. 30. A decision is expected by the end of the year or early in January, when Trump has to report census numbers to the House. Trump’s high court nominee, Amy Coney Barrett, could take part in the case if, as seems likely, she is confirmed by then. Last year, the court by a 5-4 vote barred Trump from adding a census question asking people about their citizenship. Justice Ruth Bader Ginsburg, who died last month, was part of that slim majority. Barrett would take Ginsburg’s seat.

“President Trump has repeatedly tried — and failed — to weaponize the census for his attacks on immigrant communities. The Supreme Court rejected his attempt last year and should do so again,” said American Civil Liberties Union lawyer Dale Ho, representing a coalition of immigrant advocacy groups that challenged Trump’s plan in court.

Trump left it to Commerce Secretary Wilbur Ross, who oversees the Census Bureau, to figure out how many immigrants are not living legally in each state. The outcome of the census case could affect the distribution of political power for the next 10 years. The census also helps determine the distribution of $1.5 trillion in federal funding annually. The administration told the court that the president retains “discretion to exclude illegal aliens from the apportionment based on their immigration status.”