New Delhi, Aug. 12 -- A federal court in San Francisco began hearing arguments Monday in a case that could define the limits of presidential power to use military forces in domestic law enforcement. The three-day trial centers on whether President Donald Trump's deployment of US Marines and federalized National Guard troops to Los Angeles in June violated the 1878 Posse Comitatus Act, which restricts the military from policing civilians.

Ernesto Santacruz Jr., field office director for the Department of Homeland Security in Los Angeles, testified that Immigration and Customs Enforcement (ICE) officers faced daily threats before military personnel arrived.

"We still had officer assault situations," Santacruz said. "But they did reduce dr...