This year’s Six Nations will adopt the 20-minute red cards trialled in the autumn.
For the first time in the Championship, players sent off for technical fouls can be replaced by a teammate after 20 minutes in a bid to punish the players and not the teams.
However, referees can still award full and permanent red cards for deliberate and dangerous acts of foul play.
Following its successful debut at the Autumn Nations Series, referees will continue to explain all important match decisions to spectators via microphone.
To speed up the game, kickers have 60 seconds after a try is scored to make conversions, while scrums and lineouts must be formed within 30 seconds.
A global legal trial aimed at protecting scrum-halves at the base of rucks, mauls and scrums will also come into force for the Six Nations.
The Six Nations will begin with Wales traveling to France on Friday January 31. Scotland host Italy and England travel to Ireland the following day.
