Rugby Union has become the first major contact sport in Australia to bring in comprehensive weight and height grading for juniors.

Key points: The Size for Age' policy will apply to players in Under 10 to Under 15 grades

The Size for Age' policy will apply to players in Under 10 to Under 15 grades Players can be moved a maximum of two grades

Players can be moved a maximum of two grades Decisions will be final, but players can request a second assessment at a later date

The move is designed to protect the safety of children and allow them to develop skills against players of a similar size.

Because when it comes to rugby, size does matter, as parents increasingly embrace sports like soccer over the rugby codes because of at-times huge differences in physical builds of junior players.

The Size for Age policy will this year be applied to players in the Under-10 to Under-15 grades, whereby an initial identification of 'outliers' based on weight and height is followed up with an assessment by an independent coach of a player's experience, skill level, overall fitness and maturity.

Players can then be sent down an age group or up to a maximum of two grades.

The exact parameters that will prompt an assessment will be released in the coming weeks.

'You get the best skill development'

The move comes at the end of two years of extensive research, undertaken in conjunction with Brumbies Rugby, Sydney Junior Rugby and the Australian Catholic University.

Data assessment of more than 1,500 junior players in the Canberra and Sydney systems, including video analysis of training and matches, informed the policy.

Rugby Australia rugby services head Lachlan Clark believes it will help answer parents' concerns over their children's protection and encourage youngsters to stay in the sport.

The exact parameters that will prompt an assessment will be released in the coming weeks. ( AAP: Dean Lewins, file photo )

"The changes we have made with our size and age guidelines are aimed at making the game safer and more enjoyable for all participants, while staying true to the value that rugby is a game for people of all shapes and sizes," Clark said.

"The best rugby is when players of similar physical development, skill and ability are playing against each other.

"It's the most fun, you get the best skill development, and the players want to keep playing."

Initial feedback positive

Final decisions will be mandatory, although players will have with the ability to request a second assessment at a later date, should they feel wrongly assessed.

The initial feedback has been broadly positive, with hesitancy from some players told to move quickly overcome by an increased level of enjoyment in the game, having found themselves, "playing where their skills and experience fitted", according to Clark.

Concerns over players forcibly taken away from their friends, and 'gentle giants' being stigmatised or smaller players held back, Clark insists, were given due consideration in the formation of the policy.

"Smaller skilful players can be placed exactly where they need to be," he said.

"What we're also looking at is smaller, unskilled players, and players looking to learn the game, they have the capacity to go down and gain their confidence.

"They may come back next year to their true age grade.

"This is about finding the best place for each player after they've been identified."

'Single greatest move', Russell Crowe says

The issue of weight disparities between junior football players and the inherent safety concerns was brought into focus recently by comments from actor and South Sydney Rabbitohs owner Russell Crowe.

Crowe, a prominent voice in rugby league, branded the situation of physically developed juniors bossing matches "unsafe and patently unfair," asserting that a move to gradings on size rather than age is the, "single greatest move that rugby league needs to make right now".

Across the ditch, New Zealand rugby has long had under-age games arranged on weight and height —something that clearly has been of no detriment to the development of their elite players.

Blue Card system to fully roll out in 2018

Meanwhile, Rugby Australia (RA) also confirmed the trial of their Blue Card system last year would be rolled out fully in 2018.

Blue cards will be shown to players taken off the pitch due to concussion concerns.

Once a player is shown the card by the match official, they cannot participate any further in the match and are required to undergo a mandatory medical assessment and then follow a set program before returning to rugby.

That system will be part of all rugby under RA control in the coming season, from Under-13s to the national Rugby Championship.