The suit alleges that the nation’s largest bank ran “a massive debt collection mill” to obtain default judgments and wage-garnishment orders against about 100,000 credit cardholders in California. (Peter Foley/BLOOMBERG)

As the nation’s economy struggled, JPMorgan Chase filed hundreds of lawsuits a day against Americans for credit-card default using erroneous or flimsy evidence, according to a lawsuit filed Thursday by California Attorney General Kamala Harris.

The suit alleges that the nation’s largest bank ran “a massive debt collection mill” to obtain default judgments and wage-garnishment orders against about 100,000 credit cardholders in California from January 2008 to April 2011. On one day in April 2010, JPMorgan filed 469 debt-collection lawsuits in California and then followed with 226 the next day, according to the complaint.

JPMorgan declined to comment on the suit. It comes just weeks before the company’s chief executive, Jamie Dimon, faces a vote of confidence by shareholders, some of whom have questioned his leadership after the bank suffered a $6.2 billion trading loss in 2012.

California’s top prosecutor is accusing the bank of routinely “robo-signing” hundreds of legal documents “without any knowledge of the facts alleged in the document and without regard to the truth and accuracy of those facts.” That practice was widely documented in foreclosure cases that led to multibillion-dollar settlements, including a few involving JPMorgan.

The complaint says that JPMorgan also failed to properly serve notice of debt-collection lawsuits against consumers while claiming the notices had been served, a practice known as “sewer service.”

According to the complaint, “At nearly every stage of the collection process, [JPMorgan] cut corners in the name of speed, cost savings, and their own convenience, providing only the thinnest veneer of legitimacy to their lawsuits.”

The attorney general’s office would not disclose when it began its investigation into JPMorgan’s alleged practices, because the inquiry is ongoing.

“Chase abused the judicial process and engaged in serious misconduct against California credit card borrowers,” Harris (D) said in a statement.“My office will demand a permanent halt to these practices and redress for borrowers who have been harmed.”

The complaint does not specify restitution or damages, but under California law each victim would be entitled to up to $2,500 per violation, which would total $250 million. That number could climb, because the attorney general is asking for other victims to come forward.

Reports of JPMorgan’s aggressive debt-collection practices first surfaced in the American Banker last year. The trade newspaper said the U.S. Office of the Comptroller of the Currency was investigating the Wall Street giant after a former employee alerted the regulator that thousands of delinquent accounts had incorrect balances. Officials at the office, which oversees the nation’s largest banks, declined to comment.

Consumer advocates have long warned of widespread abuses in debt collection. A report last year by Consumers Union said that debt collectors were filing an increasing number of lawsuits against borrowers without proper documentation. In some cases, companies were suing borrowers over debts that had been paid or winning court judgments without proof that they owned the debt.

The Consumer Financial Protection Bureau and the Federal Trade Commission share responsibility for enforcing federal laws to protect consumers from abusive practices. Companies in violation of those laws could face enforcement action, meaning the California case may just be the start of JPMorgan’s woes.

The CFPB takes “seriously any reports that debt is being bought or sold for collection without adequate documentation that money is owed at all or in what amount. The CFPB is taking a close look at debt collection practices to make sure that consumers are being treated fairly and the law is being followed,” an agency spokesperson said in a statement Friday.