"61 Paragraph (a) of the definition of "serious Injury" focuses on impairment or loss of body function, rather than on the injury resulting from a transport accident. A body function must not be equated with an injury, as the impairment of a person is not the same thing as the impairment of a person's body function. Paragraph (a) of the definition focuses upon impairment or loss of body function and requires that the impairment or loss be both 'serious' and 'long-term'.
62 The test for determining whether an applicant for leave under s 93(4)(d) of the Act has suffered serious long-term impairment or loss of a body function is subjective in the sense that it is the effect on the particular applicant's body function that must be considered. That determination, however, must be objectively made: it is the judge's opinion as to the seriousness of the impairment or loss - not that of the applicant or his or her medical practitioners - that is decisive.
63 In determining whether an applicant has suffered a serious long-term impairment or loss of a body function, it is impermissible to aggregate impairments or losses of different body functions. Each body function must be considered separately and a determination must be made as to whether that function has been impaired or lost and, if so, whether the impairment or loss is serious and long-term. A body function may be impaired or lost by reason of two or more injuries acting together to cause an impairment or loss.
64 The applicant has the burden of proving, on the balance of probabilities, that he or she has suffered an impairment or loss of a body function that, as a result of the infliction of the injury complained of, is both serious and long-term. In order to be 'serious', the consequences of the injury must be serious to the particular applicant in relation to either pecuniary disadvantage or pain and suffering, or both. Moreover, it must be established that the injury, when judged by a comparison with other cases in the range of possible impairments or losses, can be fairly described at least as 'very considerable' and certainly more than 'significant' or 'marked'.
65 The definition of 'serious injury' in s 93(17) of the Act intends to maintain a division between injuries with physical consequences, which fall within paragraph (a) of the definition, and injuries with mental consequences, which fall within paragraph (c) of the definition. The inquiry that must be made under paragraph (a) focuses attention on whether the injury has produced an organic impairment or loss of a body function and whether, having regard to its consequences, that impairment or loss is serious and long-term. Where an impairment or loss of a body function is produced as a consequence of a mental disturbance or disorder, that impairment must be considered under paragraph (c) rather than under paragraph (a). Where the impairment of a body function is the product of both organic and mental conditions, it will not fall within paragraph (a) unless it is predominantly the product of the organic condition.
66 The 'textual distinction' between the physical and mental consequences of an injury that is maintained by the definition of 'serious injury' in s 93(17) of the Act does not preclude a mental or behavioural disturbance or disorder from being taken into account in determining the seriousness of an impairment or loss of a body function that is held to fall within paragraph (a) of the definition.
67 A stoic applicant who has been prepared to put up with pain and suffering and make the best of his or her situation should not be treated less favourably than an applicant who, being of less strength of character, simply resigns himself or herself to the injury.
68 The endurance of permanent daily pain requiring frequent medication must, according to ordinary human experience, raise a real prospect of a 'very considerable' consequence."