Paragraphs 27(d) and 28(1)(d) of the MRCA provides that an injury, disease, or death is to be taken to be a service injury, service disease or service death if the injury, disease, or death:
was sustained or contracted while the person was a member rendering defence service, but did not arise out of that service; or
was sustained or contracted before the commencement of a period of defence service rendered by the person while a member, but not while the person was rendering defence service; and
was aggravated by any defence service rendered by the person while a member after he or she sustained the injury or contracted the disease.
Likewise, section 30 of the MRCA provides that an injury or disease is taken to be a service injury or service disease if the injury or disease:
was sustained or contracted while the person was a member rendering defence service, but did not arise out of that service; or
was sustained or contracted before the commencement of a period of defence service rendered by the person while a member, but not while the person was rendering defence service; and
a sign or symptom of the injury or disease was contributed to in a material degree by, or was aggravated by, any defence service rendered by the person while a member after he or she sustained the injury or contracted the disease.
Note that section 30 (aggravation of signs and symptoms) does not apply to claims for liability for death.
Under the MRCA, like the VEA, an aggravation of an injury or disease is not a separate injury or disease in its own right. Aggravation is excluded from the definition of injury and disease in section 5 of the MRCA. This means that, unlike the SRCA, the aggravation of an injury or disease is not to be regarded as an injury or disease in itself. That is, if a pre-existing injury or disease has been aggravated by or materially contributed to by service, that injury or disease is treated as a 'service injury' or 'service disease'. Likewise, if a pre-existing injury or disease which results in death has been aggravated by or materially contributed to by service, that death is treated as a 'service death'.
If an injury or disease is connected to service on the basis of an aggravation, the entire injury or disease becomes a service injury or service disease. However, section 5 of the MRCA establishes a particular class of service injury or service disease, classified as an 'aggravated injury or disease'. Such injuries or diseases are so classified if they qualify as service injuries or diseases via paragraphs 27(d), subsection 29(2) or section 30.
Unlike the VEA, the MRCA restricts some forms of compensation for aggravated injuries or disease to the impairment resulting from the aggravation rather than impairment from the entire injury or disease (e.g. paragraph 70(2) and section 72 of the MRCA). Some compensation and benefits under the MRCA are provided for aggravated injuries or diseases without regard to the effects of the aggravation (e.g. paragraph 43(2), subsections 61(2) and 62(2)). In other cases, compensation and benefits are only provided in respect of an aggravated injury or disease while the effects of the aggravation persist (e.g. sections 119 and 275).
The aggravation provisions of the MRCA only apply where the injury or disease which has been aggravated 'was sustained or contracted while the person was a member rendering defence service, but did not arise out of that service; or ... before the commencement of a period of defence service rendered by the person while a member, but not while the person was rendering defence service'. Therefore, in situations in which aggravation is claimed, it must be established that the onset of the injury or disease was not caused by service.