That piece of legislation was described as "unlawful" by Environment Court judge Craig Thompson at the hearing this month to consider objections from environmental groups to the way Horizons granted consents under its One Plan scheme.
The Environment Court hearing saw plenty of flak flying in Horizons direction, mainly around the notion it was giving farmers too much slack when it came to polluting waterways.
The case could be a precursor to other challenges to local authorities on how they administer consents, and has the potential for a lot of costly litigation.
It also put a spotlight on the delicate - and difficult - balance the regional council has to strike between the necessity of food production and the protection of the environment.
So as it has soaked up its share of criticism, it should be pointed out that Horizons has had its successes in cleaning up waterways.
It reports nitrogen leaching down 11 per cent overall, with 58 per cent of tested sites showing a reduction, and 80 per cent of the 85 tested swim spots in the Manawatu catchment rated "swimmable" this summer.