Judge Miller found the OIO had "materially overstated" the net benefit to New Zealand of the proposed purchase of 16 run-down farming properties, all in receivership, because it shouldn't have counted as a benefit the investment Pengxin would apply to bringing the farms back up to scratch.
The judgment has rocked previous understanding of the foreign investment regime, with Key conceding the government would not know whether it might need to change the OIO Act until it had received advice from the Crown Law Office.
Asked about the OIO's promise of a new recommendation "in a matter of days", Key said: "I saw them say that. I haven't seen that they've received Crown Law advice."
While the reassessment process might be quick, since the judge only found fault with four of the 21 areas the OIO investigated, "everyone is holding their breath" about what the judgment means for the overseas investment regime.
It was also possible that Crown Law's advice would be peer-reviewed, once received. Key stuck with his view that the judgment was unlikely to be appealed, but was more opaque on whether a law change might be required to clarify the controversial regime.
"What I care about is that we understand it so that the OIO gives the right advice and Ministers accurately understand the law," said Key. "All I care about beyond that is that it's consistent. There needs to be some predictability and transparency."
Key stressed that, based on analysis by the rich countries club, the OECD, New Zealand was one of the five or so most difficult developed countries in which to buy farmland.