The above, which translates as "not twice for the same", is one of the fundamental principles of modern law. Once you've been tried for something, and that trial has reached a final verdict (either to convict or acquit), you can't be tried for it again. And if convicted and sentenced, you can't then have additional punishments heaped on you for the same offence.
The government of New South Wales has just announced its intention to abandon that principle, with plans to subject violent criminals to indefinite detention when their sentences are complete. So, despite being handed a finite sentence by judges, these prisoners will now be given an effective life sentence by political fiat.
This unquestionably violates the rights against retroactive penalties, double jeopardy, and arbitrary detention affirmed in the International Covenant on Civil and Political Rights (and as a party to the ICCPR and First Optional Protocol, Australia will no doubt become the subject of complaints to the UN Human Rights Committee as a result) . But it also violates the rule of law. It arbitrarily changes the rules after the fact, with retroactive effects. The result is not only arbitrary decisions - criminal sentences determined by the whether a politician can gain votes by squicking someone rather than the severity of the offence - but also that no one can rely on the law as a guide to their behaviour. When sentences are arbitrary, there is no deterrence. And when they are arbitrarily large, there is no incentive to accept them (which could be unpleasant for witnesses, or those tasked with enforcement. Sadly, such injustices never seem to come back on the politicians...)
This is simply a monstrous move, but Australia has no formal human rights mechanisms which would prevent it (New Zealand has the BORA, which would at least force the politicians to admit what they were doing - not that that seems to help). And so it gets chalked up as yet another example of why Australia needs a Bill of Rights...
