After President Trump lost the 2020 election, his allies thought about what to do differently if he returned to power. One lesson from his first term, they decided, was that government lawyers, even very conservative Republican political appointees, had frequently raised legal objections to ideas he or his White House advisers put forward.

If they got another shot, they said in campaign-era interviews, they would install much more permissive gatekeepers. Now, a month into a term that has been defined by Mr. Trump’s radical challenges to the basic structure of government, his administration is moving aggressively to curb a critical internal check: independent legal thinking.

His appointees have swiftly cleared the Justice Department’s top ranks of career lawyers, even as Mr. Trump stocked leading posts with his own defense attorneys. His aides sidelined the department’s Office of Legal Counsel, bypassing its traditional role of vetting draft executive orders and giving it no acting chief. Last week, Attorney General Pam Bondi added to the purge by firing the top lawyer at the Bureau of Alcohol, Tobacco, Firearms and Explosives.

This subjugation of lawyers has now extended to the Pentagon. Late last Friday, Defense Secretary Pete Hegseth fired the top judge advocates general for the military. As three-star uniformed lawyers, they give independent and nonpolitical advice about the international laws of war and domestic legal constraints Congress has imposed on the armed forces.

Speaking to reporters this week, Mr. Hegseth appeared dismissive of the role of the senior uniformed lawyers, who serve fixed terms in nonpartisan roles and do not normally turn over when a new president takes office. Mr. Hegseth claimed none of them were “well suited” and said he did not want people who “exist to be roadblocks to anything that happens in their spots.”