6. As McHugh J explained in Brisbane South Regional Health Authority v Taylor [1996] HCA 25; (1996) 186 CLR 541 at 550-555, the discretion provided by provisions of this kind must be exercised in the context of the rationales for the existence of limitation periods. The quality of justice deteriorates with time. In almost every case in which there has been an extensive delay there will be some potential for prejudice. Crucial witnesses may have died and important documents may have been destroyed. Furthermore, the prospects of attaining just results may have deteriorated in ways none of the parties might recognise. Important, perhaps decisive, evidence may have disappeared without anybody knowing that it had once existed. Memories may have faded and the significance of those facts or circumstances that can be recalled may no longer be appreciated. Furthermore, it may be oppressive to allow an action to be brought against a potential defendant long after the circumstances that gave rise to it have passed. People should be generally free to arrange their affairs on the assumption that claims can no longer be made against them after the relevant periods have elapsed. Hence, some prejudice may be presumed even if actual instances of prejudice are not proven. Limitation periods reflect a judgment by the legislature that the general welfare of society is best served by causes of action being litigated within stipulated periods, notwithstanding the real risk that legitimate claims might thereby be defeated. Consequently, whilst an applicant may have an apparently good claim and a good explanation for not pursuing it earlier, those facts may not, of themselves, justify the exercise of the discretion in his or her favour. It is incumbent upon such an applicant to demonstrate that it is just and reasonable for the period to be extended notwithstanding the considerations mentioned. It may sometimes be a lesser evil to expose a defendant to an otherwise statute barred claim than to deprive a plaintiff of the right to have it litigated. That will often be the case when the delay has occurred without significant fault on the part of the plaintiff and when it has not occasioned any readily apparent prejudice to the interests of the defendant. On the other hand, as McHugh J observed, again at 555, the apparent justice of a plaintiff's claim will seldom be sufficient to warrant reinstating a right of action against a defendant who has been effectively deprived of the opportunity of fairly defending the claim, or has suffered significant prejudice as a result of the delay.