Thanks for the recent answers, particularly how materiality applies. Now for more on the ruck.
Watching Italy v US yesterday I noted several instances in breakdowns that I need some help interpreting.
Several times, by both teams, I would see a supporting player come into the breakdown and do what I will call a bridge over the ball (there is likely a common term for this?). By a bridge I mean the player was on hands and feet, arched over the ball. The player was clearly supporting some body weight on the hands. Now I thought that such a player had to stay on his feet, but neither the referee nor the opposing team seemed to pay any notice.
Thinking about these times a little more, I believe I would say that they were uncontested - there was no opposing player for the bridging player to bind on or push against.
Does the fact that these breakdowns are unopposed mean that "on the feet" does not apply? Or is this a case of materiality? If an opposing player decided to come forward and contest for the ball, would the bridging player be guilty of shielding the ball and preventing it from being played?
And another question about "on your feet". Many times I see a player enter a breakdown and at first he is on his feet. Then either an opposing player from the front tries to release, or push forward, and the player comes off his feet, or a teammate joins the ruck and knocks him down. How is this interpreted?
First of all Steve, please don't confuse TV Show Biz Rugby, with the Grassroots Rugby we all play on a Saturday.
"Bridging" or "Sealing Off" are illegal. But as you rightly appreciate, they may not be material if; the ball is already won, or the opposition are not contesting the ruck. It all comes down to The Rugby Ref's mantra of "only blow the clear and obvious". Remember everyone is there to play and watch rugby, not to listen to your whistle. So don't blow it unless you have to. What The Rugby Ref will do however is have a word at downtime to tell the players to stay on their feet.
Regarding your last question, it's the same answer really. If a player goes off his feet, it "may" not be his fault, but if it kills the ball he is going to get pinged, regardless of whether he jumped, or whether he was pushed! But if the ball is still available, tell him to roll away and play on.
Sometimes when a player is penalised for "not rolling away", when he is on the wrong side of a tackle or ruck, he will complain that he was trapped and unable to move. The Rugby Ref's answer to that is, "then don't allow yourself to get into that position in the first place"!
Steve, what many of your questions highlight, is that the Laws of the Game are often a framework, which the good referee uses to "manage" a game and get everyone playing rugby. It's a poor referee that sees the Laws as Black and White, to be applied whenever they are broken. This latter approach leads to a poor game of rugby and some frustrated players.
Don't ignore the law; manage it!