It presented its position in a legal filing Monday with the U.S. Court of Appeals for the 5th Circuit in New Orleans, where an appeal is pending in a case challenging the measure’s constitutionality. A federal judge in Texas ruled in December that the law’s individual mandate “can no longer be sustained as an exercise of Congress’s tax power” and further found that the remaining portions of the law are void. He based his judgment on changes to the nation’s tax laws made by congressional Republicans in 2017…

If the Justice Department’s position prevails, it would potentially eliminate health care for millions of people and cause disruption across the U.S. health-care system — from removing no-charge preventive services for older Americans on Medicare to voiding the expansion of Medicaid in most states. A court victory would fulfill Republican promises to undo a prized domestic accomplishment of the previous administration but leave no substitute in place.

The Justice Department announced the shift fewer than six weeks after William P. Barr was sworn in as attorney general. Barr, who served in the same position under President George H.W. Bush, is currently at the center of a conflict over the findings reached by special counsel Robert S. Mueller III in his investigation of Russian interference in the 2016 election — a conflict about who is entitled to view those findings, and who has the authority to make judgments about them.