Not a score for how much pain someone feels, and not a simple yes-or-no answer to whether a person can still work. An impairment rating is a medical estimate of how much permanent physical or mental function has been lost after an injury or illness has stabilized. Doctors usually express it as a percentage, often using published medical guidelines. The rating focuses on lasting loss of function in a body part or the whole person, not on job title, wages, or how frustrating daily life has become.

In practice, that percentage can carry real weight in a workers' compensation claim. It may help determine eligibility for permanent impairment or permanent partial disability benefits, and it often becomes a key point in settlement talks. A shoulder that still lifts, but not like it used to, may produce a rating even if the worker has returned to some kind of job. That is where confusion starts: "back to work" does not always mean "fully recovered."

In Maine, impairment questions in job injury cases are handled within the workers' compensation system, often under the oversight of the Maine Workers' Compensation Board. Unlike a personal injury lawsuit, fault usually is not the main issue in workers' comp, so Maine's modified comparative fault rule with a 50 percent bar generally does not control this part of the claim. Disputes usually center on the medical exam, the rating method, and whether the condition is truly permanent.