McDonald’s and several franchise owners were hit this week with seven lawsuits brought by workers in California, Michigan and New York. The details differ, but all the cases charge “wage theft” — the violation of federal labor laws, including failure to pay the minimum wage and time-and-a-half for overtime, denial of meal periods and rest breaks, and mandatory unpaid work.

The cases, filed in state and federal courts, are a bold escalation in the battle by fast-food workers for better pay and the right to unionize without retaliation, which has involved widespread strikes and protests. The lawsuits argue that both the corporate parent and the independently owned franchises where many of the plaintiffs work are jointly responsible for illegal pay practices carried out by the franchises. That strikes at the heart of the low-wage fast-food business model.

Usually, only franchises are held accountable for wage violations, because the contractual relationship between the corporation and a franchise relieves the corporation of direct responsibility for pay. But the corporate parent defines virtually all of the franchise’s nonpay business practices and in that way exerts enormous influence on pay. As a policy analyst for the National Employment Law Project recently told The Washington Monthly, “The corporations set wages by setting everything but wages.”

One of the practices detailed in the Michigan cases involves software McDonald’s provides to franchises. The software sends alerts when labor costs exceed a set percentage of sales. Bosses would respond by telling workers to clock out for extended breaks or to delay clocking in for new shifts, without paying for the wait time. According to the complaints, McDonald’s knowingly tolerates those practices because it provides the software and has continuous access to the data. Other alleged violations involve deducting the cost of uniforms from paychecks and failing to reimburse workers for uniform cleaning costs, which can push hourly pay below the minimum wage.