"Often changes in rugby seems to be top-down but it's wonderful to see grassroots up on this one," Harris said.
He said blue card was a wonderful initiative because it took all the conjecture and decision-making away from people such as coaches and players.
"It's been a clever, innovative way of going about it which Northland led and New Zealand saw its benefits," Harris' said.
With no cameras or medical professionals around at grassroots' rugby, he said blue cards would help protect players from the dangers of successive concussions. Although Harris said he felt for the referees, not only in the application of blue cards but in other areas of the law, it was they who would have the added responsibility to now assess the level of concussion.
NZRU general manager of community and provincial rugby, Brent Anderson, said it was still up to the provinces whether they took up blue card initiative but praised Northland for leading the charge.
"I think [Northland Rugby Union chief executive] Jeremy Parkinson and his crew, together with Northland referees and clubs, have introduced something which has gone well and we'll let other provinces know how Northland went with it. Anything that gives another option in terms of player safety is welcomed. It's just another tool available to make players safe and adds an extra public view," he said.
Mr Anderson said it was everyone's responsibility to ensure players were safe from head knocks.