New Zealand Rugby have opened a Pandora's box with their Brad Shields decision

It's good news for Brad Shields that he has finally gained a release agreement to play for England this June - but maybe not so good news for the Hurricanes.

Now that New Zealand Rugby have realised they had no legitimate legal lever to pull to stop Shields from representing England, the focus will soon fall on what kind of physical and emotional state the Hurricanes captain will be in once he returns from a three-test series in South Africa.

Shields has shown himself to be durable over the years. He's rarely injured, his work rate is high, his commitment obvious. He's the sort of player coaches love because they know they will get all of what he has.

But by the end of next month, after he's flown around the world and had the stress of quite absurdly beginning his test career with a 'foreign' country, what will he have left?

It's hard enough for established All Blacks to jump back into Super Rugby after a domestic June test series, so goodness knows what impact so much travel and emotional upheaval will have on Shields.

The danger here is that Shields could be drained and flat by the time he returns at a time when the Hurricanes need him at his best: energised and driven. It will be business time in Super Rugby, every game having something riding on it.

And if the Hurricanes end up feeling like Shields' England sojourn robbed him of some edge, that is when life could become quite interesting.

NZR, in announcing their decision to release Shields, remained adamant they had a strong case to not do so and were only relenting because of the previous loyalty and long service of Shields.

"We are extremely disappointed that the RFU chose to take this unusual step in seeking this release given that Brad has not yet played rugby in England," said NZR head of professional rugby Chris Lendrum.

"We are releasing Brad with our best wishes, and we hope to see him achieve his goal of playing international rugby in June."

But a precedent will have been set and other nations who are permanently hunting New Zealand's dual-qualified players will feel that if they follow England's move and ask for a Super Rugby contracted player to be released in June, they will get what they want.

And that could be dangerous for NZR.

Across New Zealand there are significant numbers of dual-qualified players who may now find it easier to commit their international allegiance elsewhere in the middle of their Super Rugby contracts, knowing NZR, despite insistence otherwise, is powerless to stop them.