Tesla chief executive Elon Musk has confirmed the company has restarted its California factory in violation of local government orders.
In an afternoon tweet, Mr Musk wrote that he would be on the assembly line and asked that he be arrested if authorities take anyone into custody.
State law allows a fine of up to 1,000 dollars a day or up to 90 days in jail for operating in violation of health orders.
The plant in Fremont, south of San Francisco, had been closed since March 23 under orders to prevent the spread of coronavirus.
Early on Monday, the car park was nearly full at the massive plant, which employs 10,000 workers, and transporters were driving away loaded with vehicles that may have been produced before the shutdown.
The restart violates orders from Alameda County Health Department, which has deemed the factory a non-essential business that should not open under restrictions intended to help stop the spread of the coronavirus.
Alameda County Sheriff Sergeant Ray Kelly said any enforcement of the order would come from Fremont police. Geneva Bosques, Fremont police spokeswoman, said officers would take action at the direction of the county health officer.
The Health Department said on Saturday that it was in talks with Tesla to reopen the plant safely.
The restart came two days after Tesla sued the county health department seeking to overturn its order, and Mr Musk threatened to move Tesla’s manufacturing operations and headquarters from the state.
Tesla contends in the lawsuit that Alameda County cannot be more restrictive than orders from California governor Gavin Newsom. The lawsuit says the governor’s coronavirus restrictions refer to federal guidelines classifying vehicle manufacturing as essential businesses that are allowed to continue operating.
“Frankly, this is the final straw,” Mr Musk wrote in a now-deleted tweet. “Tesla will now move its HQ and future programs to Texas/Nevada immediately.”
He wrote that whether the company keeps any manufacturing in Fremont depends on how Tesla is treated in the future.
The Bay Area order calls for limited return of business and manufacturing, with health restrictions, starting on May 18, the same day Detroit car makers plan to restart assembly plants.
Mr Newsom has repeatedly said that counties can impose restrictions that are more stringent than state orders. Alameda County was among six San Francisco Bay Area counties that were the first in the nation to impose stay-at-home orders in mid-March.
Early in the coronavirus crisis, the governor praised Mr Musk as the “perfect example” of the private sector assisting the state in the pandemic, after Mr Musk pledged to provide more than 1,000 ventilators to California hospitals, a fact Mr Newsom repeated often and called a “heroic effort”.
But whether the Tesla chief made good on the promise remains in dispute. Several weeks after Mr Newsom was touting the ventilators, the state said it had not heard of any being delivered.
Mr Musk responded, demanding on Twitter that Mr Newsom correct the record and sharing tweets and screenshots from hospitals and Los Angeles County thanking him for sending supplies.
He has been ranting about the stay-home order since the company’s April 29 first-quarter earnings were released. He called the restrictions fascist and urged governments to stop taking people’s freedom.