The Posse Comitatus Act is a nearly 150-year-old federal law that limits the U.S. military’s role in enforcing domestic laws. At its core, experts say the law reflects America’s long-standing belief ...

[This post is co-authored with Professor Seth Barrett Tillman.] The Supreme Court's decision in Trump v. Illinois (2025) was issued in a preliminary context, and without the benefit of oral argument.

If you’ve been paying attention to President Donald Trump’s vows to deploy active-duty soldiers to police American cities, mainly governed by Democrats, then you’ve probably heard two words pop up ...

A federal judge in California has ruled that President Donald Trump’s deployment of the National Guard to Los Angeles this summer was illegal. The decision comes as Trump moves to expand the use of ...

Old Law, New Problems: Origins and Purpose of the Posse Comitatus Act The act is now being used to challenge actions by President Donald J. Trump, who has sent federal troops into U.S. cities, and ...