Diogenes
Nemo me impune lacessit
This is stated in Article IV, Section 4, often referred to as the Guarantee Clause.
It mandates that the federal government ensure each state maintains a government consistent with republican principles—broadly understood as a system where the people hold sovereign power through elected representatives.
Beyond this, the clause also obliges the federal government to protect states against invasion and, upon request, against domestic violence, though these are conditional rather than absolute duties.
While the Constitution outlines many powers and responsibilities—like taxation, defense, and regulating commerce—the Guarantee Clause stands out as the sole explicit "duty" framed as a direct obligation.
Other functions, like conducting a census or establishing courts, are authorized but not mandated in the same imperative language.
Historically, this clause has been interpreted narrowly, with courts rarely enforcing it directly, leaving its practical scope more theoretical than actionable. Still, it’s the closest the Constitution comes to assigning a singular, unavoidable job to the feds.
@Grok
