World Rugby plans to downgrade red as part of several law changes
Under the proposed change, when a team loses a player to a red card they can bring on a replacement after 20 minutes.
Mauls can only stop once before the team with the ball has to move it away.
Scrum-halves will receive what World Ruby called "enhanced protection... at scrums, rucks and mauls."
Other proposals are designed to speed up the game, with 30-second scrum and lineout put-in limits add timed conversions.
At lineouts, if the ball is not thrown in straight but the opposition does jump, play will continue.
World Rugby tested the rules in the recent Rugby Championship, Pacific Nations Cup and Women's XV tournament.
It said that in the trial games, playing time was "up by more than two minutes and 30 seconds, reaching more than 33 minutes per match" while matches took up to five minutes less to finish.
The World Rugby Council is due to vote on the changes on November 14.
"These trials demonstrate our commitment to making rugby as enjoyable as possible for audiences," said World Rugby chairman Billy Beaumont.
