Essentially in my book, there's been 3 separate incidents of potential foul play by English players in this 6 Nations, which all could've been a ban of some sort. Yet somehow not a single, even just a week, ban has been put on them.
The number of incidents is irrelevant. There is no concept of team citings / bans like there is with yellow cards during a match each incident of
potential foul play is assessed individually on its merits. As I understand it, the process is that if the citing officer believes that an incident was worthy of a
red card, the incident will be referred to the citing commission who will decide if they agree and apply what they believe to be an appropriate ban.
In Marler's case, it doesn't appear that is was believed that either incident would have resulted in him being red carded, so due process has been followed. Seeing as Francis' actions (apparently) didn't merit a red, it seams reasonable that neither of Marler's would have. Saying that, I don't think that Joubert's performance should be a barometer for the game as a whole. However in this instance, you could argue that this process is flawed. I think that most would agree that both of his transgressions were worthy of a yellow card. Had both incidents been spotted and cards been handed out, Marler would have received a red and copped at very least a one week ban.
The Brown incident has been done to death elsewhere. My memory of the discussion was that if you were an English supporter, Murray shouldn't have been holding on, if you support anyone else, Brown was trying to maim Murray! I like to think that I'm able to be pretty objective in situations like this and have tried to use the laws / guidelines to try to aid this. In this situation, the laws aren't all that helpful - all they say is "though shalt not kick an opponent" and prescribe a penalty kick (obviously the referee has cards at his discretion, but the laws give not guidance as to when to use them). The foul play guidelines don't really deal with this kind of incident, they give sanctions for stamping and trampling, but from memory, this requires a deliberate downward motion of the boot onto an opponent. All of this being the case, I don't see it as a clear red card offence and don't know what sanction they could have applied had he been cited, so once again can make my peace with the decision.