Walmart Inc. will have to face a certified class of job applicants alleging it conducted background checks without their permission, a federal court ruled Jan. 17.

Whether Walmart made disclosures required by the Fair Credit Reporting Act can be answered on a classwide basis, Judge David O. Carter wrote for the U.S. District Court for the Central District of California.

The class includes about 5 million members, according to the plaintiff’s estimates. The FCRA allows statutory damages of up to...