"Today is a significant escalation in the federal government's effort to confront the resistance of sanctuary cities," Barr said.
Barr is seeking to have a federal court toss out the new California law that bans for-profit immigration detention centers.
Barr contends that California doesn't have the constitutional authority to interfere with federal immigration operations.
"California has every right to decide how it wants to manage its own prisoners and detainees, but it has no authority to dictate to the federal government how it conducts its federal operations," he said.
But Assemblyman Rob Bonta (D-Oakland), who wrote the law, begged to differ with Barr's claim.
"When there is a private, for-profit corporate actor that is hurting our people, harming them, we can't just be expected to stand by," he said. "You can't use the supremacy clause and say you must stand by while a private, for-profit corporation abuses your people."
Barr described California's law as illegally protecting so-called "criminal aliens" at the expense of American citizens.
Bonta said the federal government's position is not based on reality.
"They peddle in fear, not facts," he said. "This isn't just an ideological belief. This is based on data and statistics. The federal government's own data on every single metric. For-profit private prisons and detention centers hurt and harm the health, safety and welfare of those in their system."