DEMOCRACY WATCHTrump’s National Guard Deployments Reignite 200-Year-Old Legal Debate Over State vs. Federal Power
If you’re confused about what the law does and doesn’t allow the president to do with the National Guard, that’s understandable. The conflict between the Trump administration and states such as Oregon and Illinois throws into relief a question as old as the Constitution itself: Where does federal power end and state authority begin?
If you’re confused about what the law does and doesn’t allow the president to do with the National Guard, that’s understandable.
As National Guard troops landed in Portland, Oregon, in late September 2025, the state’s lawyers argued that the deployment was a “direct intrusion on its sovereign police power.”
Days before, President Donald Trump, calling the city “a war zone,” had invoked a federal law allowing the government to call up the Guard during national emergencies or when state authorities cannot maintain order.
The conflict throws into relief a question as old as the Constitution itself: Where does federal power end and state authority begin?
One answer seems to appear in the 10th Amendment’s straightforward language: “The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people.” This text is considered to be the constitutional “hook” for federalism in our democracy.
The founders, responding to anti-Federalist anxieties about an overbearing central government, added this language to emphasize that the new government possessed only limited powers. Everything else – including the broad “police power” to regulate health, safety, morals and general welfare – remained with the states.
Yet from the beginning, the text has generated plenty of confusion. Is the 10th Amendment merely a “truism,” as Justice Harlan Fiske Stone wrote in 1941 in United States v. Darby, restating the Constitution’s structure of limited powers? Or does it describe concrete powers held by the states?
Turns out, there’s no simple answer, not even from the nation’s highest court. Over the years, the Supreme Court has treated the 10th Amendment like the proverbial magician’s hat, sometimes pulling robust state powers from its depths, other times finding it empty.
10th Amendment’s Broad Range
The arguments over the 10th Amendment for almost 200 years have applied not only to the National Guard but to questions about how the federal and state governments share powers over everything from taxation to government salaries, law enforcement and regulation of the economy.
For much of the 19th century, the 10th Amendment remained dormant. The federal government’s weakness and limited ambitions, especially on the slavery question, meant that boundaries were rarely tested before the courts.
The New Deal era brought this equilibrium crashing down.
