Speaking to U.S. attorneys in 1940, Attorney General Robert H. Jackson reflected on the enormous scope of prosecutorial power and the crucial importance of shielding it from politics.

“The prosecutor has more control over life, liberty and reputation than any other person in America,” Mr. Jackson, who would go on to be a Supreme Court justice of rare distinction, wrote in a text that is taught to law students and circulated to young lawyers.

Sharply differing interpretations of the classic 85-year-old speech, “The Federal Prosecutor,” figured prominently in an extraordinary exchange of letters on Thursday that led to the resignation of Danielle R. Sassoon after she refused to carry out the Trump administration’s command to drop the corruption prosecution of New York City’s mayor, Eric Adams.

The two views reflect a schism in conservative legal thought over how prosecutors, now working for a Trump-led Justice Department, should balance their duty to obey orders from superiors with their obligation to follow their best understanding of the law. One view emphasizes caution, deliberation, and independent and decentralized judgment, while the other values top-down vigor in the service of policy goals that can seem transactional if not unprincipled.

The split could reshape not only the relationship between federal prosecutors around the country and their bosses in Washington, but also the limited but real discretion enjoyed by all sorts of other officials throughout the government. Thursday’s events, in other words, are emblematic of the ethos of the second Trump administration, one that requires federal workers to fall into line or be fired.

Ms. Sassoon, whose resignation led to a cascade of others, cited Mr. Jackson’s speech to argue that the administration’s directive was not the product of a good-faith difference of opinion but an assault on the rule of law.