Trump vs Newsom showdown lands in court with family ties to the nation's highest bench

The federal government argued before a California judge -- the brother of a retired Supreme Court justice -- that President Donald Trump acted within his legal authority by deploying the National Guard and Marines to quell immigration riots in Los Angeles earlier this year.

Judge Charles Breyer - sibling of President Bill Clinton-appointed Justice Stephen Breyer - heard testimony in the case brought by the Newsom administration over whether the federal government violated federal law in its use of the military on domestic soil and/or the 10th Amendment.

The case is expected to test the limits of a president's power as commander in chief, as the 1878 Posse Comitatus Act - born out of Reconstruction - requires either an act of Congress or constitutional authorization to use the U.S. military for domestic law enforcement.

The penalty under that act is a prison term of two years and a fine, at most.

TRUMP AND NEWSOM FIGHT OVER NATIONAL GUARD HEADS TO TRIAL IN CALIFORNIA

In the 1997 case of Printz v. U.S., Justice Antonin Scalia ruled in favor of two county sheriffs in declaring that the federal government has no authority to commandeer or compel local law enforcement to take special actions.

However, in Martin v. Mott, Madison-appointed Justice Joseph Story wrote in a 6-0 opinion that the president has sole authority to determine when emergency use of state militias (national guards) is appropriate.

In court, Breyer said his ultimate decision will have far-reaching consequences for how presidents, including Trump, can deploy assets in other cities, Politico reported - as the president used the District of Columbia's unique 1970s charter to briefly take control of its police force this week.

Acting Los Angeles ICE Director Ernesto Santacruz Jr. testified Monday that he received multiple reports of his officers being attacked in the days leading up to Trump's deployment.

"We still had officer-assault situations, but they did reduce drastically" after Trump took control of the situation, he said.

FEDERAL JUDGE ASKS IF NATIONAL GUARD DEPLOYMENT IN LOS ANGELES VIOLATES POSSE COMITATUS ACT

However, Breyer has said the anti-immigration riots fell "far short of rebellion" - in terms of what would constitute federal intervention permitted under Posse Comitatus.

Newsom has argued that Trump went far afield of the 1878 law and violated the purview of California's governor to control his own National Guard.

California National Guard Commander Maj. Gen. Scott Sherman testified Monday that he had opposed the request on Father's Day for assistance in an operation that day, citing a minimal threat-assessment to officers at the time.

U.S. Customs & Border Patrol El Centro Sector Chief Agent Gregory Bovino did not agree with that assessment, according to reports of Monday's testimony.

CLICK HERE TO GET THE FOX NEWS APP

The trial comes as a related Washington, D.C., situation comes to a head, with Trump using the city charter to attempt to bring order to the District.

U.S. Attorney for the District of Columbia Jeanine Pirro warned Monday that too many offenders - particularly juveniles - are getting away with violent crimes against innocent civilians.

"Young people are coddled, and they don't need to be coddled anymore. They need to be held accountable. They shouldn't be going to arts and crafts and family court," she said, as the Trump administration issued a verbal indictment of the D.C. City Council's lax law enforcement posture.