In the wake of the acquittal in the Kahui case, the government has been pushing hard for the passage of its Criminal Procedure Bill, which would, among other things, undermine the prohibition on double jeopardy by allowing those acquitted of a crime to be retried if their acquittal was tainted by perjury or witness intimidation or if "new and compelling evidence" emerges implicating them in the offence. But while the former seems fair enough, the latter would be a gross mistake. And the main reason why can be summed up in just three words: "Arthur Allan Thomas". In the past, members of our police force have manufactured and planted evidence to get someone they deemed guilty. This change would give them a clear incentive to do so again. And that is not something we should tolerate.
Allowing an exception for "new" evidence would also allow the police to get away with lazy policework (why bother doing a good job and exploring all avenues when you can whine about "crims" "getting off" and come back for a retrial), while allowing the endless persecution of the innocent. We shouldn't tolerate that either. If we're worried about the guilty going free, then the answer is to make sure the police do their fucking jobs properly, not lower the bar and encourage them to stitch up the innocent.