A U.S. District Court has ruled that Walmart had violated minimum wage laws by failing to adequately pay its drivers for all of the time they actually worked, according to a report by the Fresno Bee.

The judge  determined that the drivers must be paid for all required tasks and time.  The drivers in the case asserted that they had not been paid for tasks such as waiting to load or unload cargo, fill out mandated paperwork or maintain their vehicles.

Walmart will be required to pay back pay to all of the 720 drivers represented in the case, which could end up costing the company $100 million or more, according to the report.

For its part, Walmart plans to continue fighting the claim, saying that its drivers are among the highest paid in the trucking industry. The drivers’ attorney in the case claims that unlike in other states where pay per mile is allowed, California law requires drivers to be paid for all of the tasks they’re given.

Also, court documents cite Walmart policies that required drivers to stay in their vehicles during layovers, for which they were paid $42 dollars for a 10-hour period.

“The Court finds that the policies in the Driver Pay Manuals subjected drivers to Wal-Mart’s control during layover periods,” stated Judge Susan Illston in the court documents. “Under California law, the drivers must be paid for all of the time that they were subject to Wal-Mart’s control.”