What criteria must be met to determine a dangerous offender's sentence?

55. These criteria seem to me to be no less pertinent reflections of society's concerns in releasing dangerous offenders than they are in releasing other offenders. The fact that dangerous offenders may be less likely to satisfy these requirements is primarily a function of their dangerousness, not of the punishment imposed. Of course, the imposition of an indeterminate sentence may, like all sentences, sap the will of the offender to rehabilitate himself or herself. However, I would have thought the incentive to reform is far greater, at least theoretically, in the case of a dangerous offender. In this regard, I note that the availability of parole has been seen to validate mandatory life sentences in the context of similarly motivated legislation in the United States (see Solem v. Helm, supra, per Powell J., for the majority).