The watchdog has barked - at long last. No longer is it an inoffensive pooch whose mutterings could be easily dismissed or simply ignored. The hound is now displaying some real teeth. And the Prime Minister may yet be the one who ends up getting badly bitten.
Cheryl Gwyn, the inspector-general of Intelligence and Security, has been in the job for little over three months. On her appointment to the long-standing and recently beefed-up oversight role, she set an objective for her three-year term: restoring public confidence that the Security Intelligence Service and its sister agency, the Government Communications Security Bureau, were truly subject to rigorous scrutiny and were not breaking the laws under which they operate.
The highly experienced lawyer could never have envisaged the SIS's handling of an Official Information Act request from an Auckland-based blogger being the first test of just how serious she is in seeking such a transformation.
Given it is always easier to get blood out of a stone than meaningful information out of the SIS or GCSB, the rapid and positive response to Cameron Slater's request for politically sensitive material of potential embarrassment to former Labour leader Phil Goff - as detailed in Nicky Hager's Dirty Politics - was puzzling and disturbing.
It was disturbing because Slater undisputedly got preferential treatment, receiving the material before journalists who made similar OIA requests.
Hager's book cites Slater's emails which leave the reader to draw only one conclusion - that Slater was tipped off about the material and told how to request it so he got it quickly.
Only officials or staff in the SIS, the Department of Prime Minister and Cabinet or the Prime Minister's office - all of which fall under John Key's responsibility - could be culpable. If someone from either of the first two departments was in collusion with Slater, then that amounts to a serious case of the polticisation of the public service.
If the latter office was orchestrating the release of the material, then it was being done for political purposes and was an abuse of power.
Gwyn has now deemed there is "sufficient public interest" to justify her holding her own inquiry to get to the bottom of what happened.
It is a hugely significant and - given the current acute political sensitivities surrounding Hager's book - unprecedented step for her office to take.
Gwyn is to be applauded for having the gumption to dive into the deep end of a political brouhaha of such messy but high-stakes proportions.
It seems unlikely she will have enough time, however, to complete her inquiry and release her findings in the little over four weeks left until the election.
And for that, the Prime Minister - locked in the political fight of his life on a number of fronts - could yet end up being extremely grateful.
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