Clip 2 - 17 September 2018 - Law 3
On 47 minutes, Jaco Visagie, the Blue Bulls hooker, is sent to the sin bin for tackling Kyle Steyn without the ball. Play goes on without any change till Griquas are penalised and Manie Libbok kicks out for an attacking line-out, Blue Bulls' throw-in.
Then the Blue Bulls' replacement hooker, Edgar Marutlulle, runs onto the field to take the throw-in into the line-out and flank Jano Venter comes off so that the Blue Bulls still played on a man short, as the sin-binning required them to do.
Law 3.16: When a front-row player leaves the playing area, whether through injury or temporary or permanent suspension, the referee enquires at that time whether the team can continue with contested scrums. If the referee is informed that the team will not be able to contest the scrum, then the referee orders uncontested scrums. If the player returns or another front-row player comes on, then contested scrums may resume.
Before the law rewrite, the wording was more precise on replacing a front-row player, and there is supposed to be no change in law in this regard because of the rewrite.
Law 3.5 (n): After a front-row player leaves the field of play or is sent off, or during the time for which a front-row player is temporarily suspended, the referee, upon awarding the next scrum, will ask the player's captain, whether or not the team has another player on the playing area who are suitably trained and experienced to play in the front row....
After Visagie is temporarily suspended, there are no scrums till Marutlulle comes onto the field to throw into a line-out.
The difference, in this case, is that it is a Currie Cup match and rolling substitutions are allowed in a Currie Cup match. And so Marutlulle was allowed to replace Venter at that time or at any other time during the match.