This year’s Six Nations will implement the 20-minute red card system that was trialled in the autumn.
For the first time in the Championship, players sent off for technical violations can now be replaced by teammates after 20 minutes, in an initiative designed to punish players rather than teams.
However, the referee may award a full and permanent red card for intentional and dangerous fouls.
Even after a successful debut in the Autumn Nations Series, referees will continue to use microphones to explain important decisions during games to the audience.
To speed up the game, kickers have 60 seconds after a try is scored to convert, and scrums and lineouts must form within 30 seconds.
A global legal challenge aimed at protecting scrum-halves at the base of rucks, mauls and scrums will come into force during the Six Nations.
The Six Nations begins with Wales’ trip to France on Friday 31 January, followed by Scotland hosting Italy and England traveling to Ireland the following day.
