Volunteer firefighters — as well as other workers — may qualify as employees under anti-discrimination law even if they don’t receive a paycheck, a federal judge has ruled. In a written opinion, U.S. District Judge Joan B. Gottschall rejected the argument that volunteers must show they were compensated for their work in order for courts to even consider whether they qualify as employees. Instead, Gottschall wrote, compensation — in the form of wages or substantial benefits — is just one …