Last Employer Rule Law and Legal Definition

Last employer rule is a legal principle that states that an employer is liable for an occupational injury or illness for exposing a worker or employee to injurious substance just before the first onset of the disease or injury. It is also known as last injurious exposure rule.

The last employer rule is an equitable doctrine. Under the last employer rule, liability resulting from injurious exposures during more than one period of employment was assigned to that employer who had last exposed an employee prior to the employee's awareness of a disease. The last employer rule is not an aggravation rule and governs where a covered worker suffers from an occupational disease. Apportionment is not an option, because the purpose of the last employer rule is to avoid the complexities of assigning joint liability and it calls for a single employer to be liable.[Far West Insulation v. Director, Office of Workers Compensation Programs, 1997 U.S. App. LEXIS 18901 (9th Cir. July 21, 1997)]