California Gov. Jerry Brown, who oversees the world’s sixth-largest economy, is not to be trifled with, as President Donald Trump probably has learned. The two are at loggerheads over immigration enforcement. We are often inclined to take Brown’s side, but he’s dead wrong on the “sanctuary” immigration measure California has enacted.

In January, a new law called Assembly Bill 450 began banning businesses from sharing important information about their employees with federal immigration authorities. Employers may not reverify the immigration status of their employees unless specifically required by federal law. Companies may not voluntarily consent if immigration authorities seek access to their premises without a warrant. If employers do allow it, they can be fined up to $10,000.

The law is rife with constitutional questions that probably will wind up before the U.S. Supreme Court. It seems unlikely that the court would take California’s side in a battle over federal authority to enforce immigration laws. A law that specifically bans employers from cooperating with federal authorities also runs roughshod over the business owners’ rights.

But the bigger flaw in Brown’s thinking when he signed AB 450 was the assumption that all employers are good people who only want to give hardworking immigrants a job. In fact, lots of employers are abusive and hold their immigrant employees in virtual captivity, knowing they can pay slave wages and their employees won’t dare complain for fear of being outed to the authorities.

Not only does AB 450 protect those bad employers, it requires them to continue operating in secret while defying federal intervention that might expose their practices. California’s sanctuary law inadvertently gives sanctuary to abusive employers.

Abuses are not imaginary. The Associated Press reported from Syracuse, Kan., recently about a ranch where conditions of servitude reportedly exist for immigrants. According to former workers, the Fullmer Cattle Co. made them keep working to pay off debts, listed as “cash advance payments,” that actually were costs incurred by the company to help smuggle the workers into the country. Immigrants were subjected to 15-hour workdays and six-day workweeks for take-home pay of around $200. A company attorney denied the allegations.

But labor leaders say immigrant workers often are subjected to exploitative, slave-like conditions imposed by employers who know how to play on workers’ fear of deportation. All of these abuses once again demonstrate the need for comprehensive reform of federal immigration laws.