Ball not released... When a ball carrier has been tackled to the ground, they have to let go of the ball. No excuses - the laws say so, so you've got to release the ball. But oftenplayers purposely hold onto the ball when they have gone down in a tackle. This is to stop the other team getting hold of the ball and starting a quick attack. But if the referee sees a player holding onto the ball on the ground, he will immediately award a penalty to the opposing team.

Handling on the ground... This is one the most important rules of rugby union. Only players standing on their feet are allowed to handle the ball. So that means that no player lying on the ground is allowed to touch the ball. This is very important in Rucks, especially after a Maul has gone to ground or direct from a tackle.

Dangerous Rucking/Stamping... Often on TV you will see a player doing what looks like a stamp in a Ruck. Although this looks totally dangerous, it is allowed in the laws of the game as long as the player is trying to "ruck" the ball. That means they are trying to release the ball which has become trapped under a number of players. But if the referee thinks the player is Rucking too close to players on the ground, then he will award a penalty for dangerous play. So be careful when you are trying to get the ball out of a Ruck - make sure you are doing it safely.

Bringing down a maul... Mauls often turn into Rucks when the player carrying the ball falls to the ground because of all the pushing and shoving going on. However, no player can bring down a Maul on purpose. This is because it could be very dangerous and cause serious injuries to those players fighting to get their hands on the ball. So if the referee believes a player has brought a Maul down, he will award a penalty at the place where the offence happened to the other team.