Will the U.S. Supreme Court permit the Trump White House to add a citizenship question to the 2020 census? Court watchers regularly caution against drawing conclusions from oral arguments. Yet, with the stakes so high and the court’s conservative majority on Tuesday appearing ready to side with the executive, it is worth highlighting the immense risk of harm in delivering such a ruling.

Three federal trial judges already have ruled against the White House. In doing so, they exposed the dishonesty of Wilbur Ross, the commerce secretary who has been pushing hard for a citizenship question. Ross has claimed that he moved to add the question in response to a request from the Justice Department. He argued Justice wanted the question to help with enforcing the Voting Rights Act. As the judges noted, the record indicates otherwise. It establishes that Ross pressured the department to go along.

The record also reveals that Ross consulted with Steve Bannon, the former White House chief strategist who has been a proponent of the president’s get-tough-on-immigration approach. Justice Sonia Sotomayor got it right in suggesting Ross went looking for a justification.

The trial judges saw more than a lack of credibility or a policy change. They cited violations of the law. For instance, Ross collided with the federal Administrative Procedures Act in failing to take into adequate account the thinking of experts within the Census Bureau, their conclusions driven by much research. Those experts, along with many others, warn that the addition of a citizenship question would discourage participation and increase the cost of conducting the census.

This expertise deserves particular notice in view of the White House argument before the high court that it is attempting little more than to weigh costs against benefits in pursuit of the correct balance. So, yes, the White House concedes, some residents would not be counted due to the citizenship question. It then adds the positive results for the Voting Rights Act would outpace the harm. The trouble is the consensus of experts disagrees. If the job amounts to a cost-benefit analysis, shouldn’t the experts take the lead?

In his way, Justice Samuel Alito essentially answered yes, as he admitted at one point, “This gets really, really technical.”

The Constitution is clear in calling for an “actual enumeration” every 10 years of those residing in the country and for the U.S. House to be apportioned based on “the whole number of persons in each state.” The census has operated without a citizenship question since 1950 because of evidence-fueled concerns about an inaccurate count. The modeling indicates that as many as 6.5 million people would not participate in 2020.

The consequences of such a shortfall would be huge, given that the federal government routes nearly $900 billion a year to states based on census data. Consider, too, that Asian and Hispanic households would be most affected, their reluctance already heightened by the nativist rhetoric and policies of the president. Democrats hardly stretch things when they argue that a citizenship question would politicize the census, amounting to another bid by many Republicans to play hardball on redistricting.

As Ilene Shapiro, the Summit County executive, recently suggested on this page, there are ways to overcome the question, mostly through an education campaign about the census. Yet that shouldn’t be necessary. There are other vehicles for gathering citizenship information. The first purpose of the census is an accurate count. A citizenship question all but ensures that won’t be the result.