Most workers compensation legislation effectively removes the right of injured workers to sue their employer (the insured) for injuries sustained while on the job. Despite this, an employer may face a lawsuit in cases involving workers that are not covered by workers compensation legislation, such as occasional workers or when a worker may be doing a task outside of their regular duties. You will want to ensure your contractors/consultants carry contingent employers' liability coverage if they use employees with other duties or occasional workers to complete work under the contract.
MIABC