Gov. Gavin Newsom alleges the Trump administration broke a 19th Century law when it sent troops to L.A. with military security perimeters and alleged apprehensions of civilian protestors.

President Donald Trump threatened to send the National Guard into San Francisco, prompting pushback from Governor Gavin Newsom, city leaders, and residents, who argued that the city is becoming safer and cleaner.

If President Trump deploys troops to other American cities, experts say it would be a clear departure from founding principles and invite a legal challenge.