Ball back is a piece of terminology

Terminology

Terminology is the study of terms and their use. Terms are words and compound words that in specific contexts are given specific meanings, meanings that may deviate from the meaning the same words have in other contexts and in everyday language. The discipline Terminology studies among other...

 in both codes of rugby football

Rugby football

Rugby football is a style of football named after Rugby School in the United Kingdom. It is seen most prominently in two current sports, rugby league and rugby union.-History:...

.

In both codes of rugby, if the ball enters touch, then play is restarted (either by a line-out

Line-out

A line-out is the means by which, in rugby union, the ball is put back into play after it has gone into touch. It is the equivalent of the throw-in in soccer. Rugby league abolished line-outs in 1897...

 in rugby union

Rugby union

Rugby union, often simply referred to as rugby, is a full contact team sport which originated in England in the early 19th century. One of the two codes of rugby football, it is based on running with the ball in hand...

 or a scrum

Scrum (rugby)

Scrum , in the sports of rugby union and rugby league, is a way of restarting the game, either after an accidental infringement or when the ball has gone out of play...

 in rugby league

Rugby league

Rugby league football, usually called rugby league, is a full contact sport played by two teams of thirteen players on a rectangular grass field. One of the two codes of rugby football, it originated in England in 1895 by a split from Rugby Football Union over paying players...

) level with the point where the ball left the field of play. The exception to this is if the ball is kicked into touch without first bouncing inside the field of play (on the full). In this case, the scrum or line-out is taken from level with the place from where the ball was kicked from, and not from where it entered touch.

Ball back is waived in certain circumstances:

• If a side elects to kick a penalty
  Penalty (rugby)
  In rugby football, the penalty is the main disciplinary sanction available to the referee to penalise players who commit deliberate infringements. The team who did not commit the infringement are given possession of the ball and may either kick it towards touch , attempt a place kick at goal, or...
  
  into touch
• If the kicking player is inside his own 22m line when he kicks the ball, and (under the ELVs) the ball has not been immediately passed or run back into the 22 (rugby union only)