Just ask the Waratahs, who are tweaking their pre-season plans around what they predict will be the new reality of professional rugby: operating with 14 or 13 players on the field at some point during each game.

NSW defence coach Nathan Grey believes there is little else to conclude after reading the new laws, which take a zero-tolerance approach to contact with the neck and head, and observing them in action in Europe.

"In terms of management from a coach's perspective, you've got to prepare a bit more for having 14 guys on the field because it's going to happen," Grey said.

"They've said those accidental things that happen you're going to get carded for, so you need to prepare that way to have 14 or 13 guys on the field a little bit more. You've got to make sure you're ready for that."

Grey, a former Waratahs and Wallabies centre, supports the reforms and vouched on Thursday for the work and planning behind their implementation.

"The golden question is the consistency around how they deliver on that," he said.

"It's going to be hard, but I think the reasonings around why they've done it and why it's in place is the right reason. They're trying to do the right things by the players, which is great, and the referees and the administration side of things, they've done a really thorough process and they're delivering it in a way that makes us confident as coaches to say 'OK, that's what they've said they're going to be looking at, and what the expectation is around that'.

"There's going to be some feeling out during the trials and into the first couple of rounds of Super [Rugby], but the consistency is the biggest thing and that's all you hope for."

The new laws, which mandate a yellow card for reckless contact with the head, come into effect at the Sydney Sevens in three weeks' time. They will also be implemented during Super Rugby trial matches, which start in the first week of February, before the season proper starts on February 23.

They have been received controversially in Europe after taking effect on January 3 in the English Premiership and Pro12, with a raft of high-profile commentators and former players questioning their wisdom and, more pointedly, their implementation by referees.

Players making accidental contact with the head will be penalised, while anything deemed "reckless" will attract a yellow card – mandating 10 minutes in the sin bin – or a red card, meaning an early shower for the offending player.

Players will be punished even if the tackle starts below the shoulder and slips upwards, or if the ball carrier slips into the tackle.

Grey said the Waratahs were looking carefully at their technique, particularly at the ruck and breakdown.

"You never coach to target the head anyway, so from that perspective it's not a massive change," he said. "It's more having that awareness, particularly around your clean-out, that if you're engaging the upper half of the body you have to make sure that you go nowhere near the head. That's pretty easy for the players, in terms of just drilling that."