A new, more worker-friendly test for determining who is a legal employee applies to more than just wage-and-hour claims, according to a May 3 opinion letter issued by California’s labor commissioner.

California has some of the most pro-worker labor policies in the nation, and the bulk of those rights and protections are triggered by formal classification as an “employee.” The guidance means the new test will be applied when workers labeled as independent contractors file complaints to the labor department for things like unpaid wages, reimbursement for business expenses, and meal and rest periods.

The letter clarifies for employers and...