Recurrence Versus Aggravation of a Prior Work-Related Injury
If you had a work-related injury and then sustain a second injury, you are likely to have to deal with two different insurers, each of which is claiming that the other is liable. To decide this question, the case law differentiates between a "recurrence" of a prior problem and an "aggravation" of the old injury. A recurrence generally means that you have had a continuity of symptoms. By contrast, an aggravation occurs when your condition is worsened to the slightest extent by the new injury.
The standard applied in this situation is known as the "the successive insurer rule." It provides that "the insurer on the risk at the time of the second injury must be held liable to pay compensation for an incapacity following that injury where there is a causal connection between that injury and the incapacity . . . " Rock's Case, 323 Mass. 428, 429 (1948). This rule applies "even if the aggravation is only a contributing cause of the disability 'to the slightest extent' to sustain a claim against the successive insurer." Simmons v. Evergreen Landscaping & Nurseries, 10 Mass. Workers' Comp. Rep. 6, 7 (1996). Thus, the second insurer will be held liable so long as there is a causal connection between the second injury and the incapacity even though "the earlier injury may have been a contributing cause or even the major contributing cause." Morin's Case, 321 Mass. 310, 312 (1947).
As a practical matter, where an employee had a pre-existing work-related injury and then has problems in the same body part, he or she should file claims against both insurers. That way, the employee stands a greater chance of obtaining benefits from one of the insurance companies.