Here is a perfect example of a back block: https://www.youtube.com/watch?v=iKODJigqR-I
Please try to *not* get distracted by the adorable small referee (it's not me by the way. There are other adorable referees around. Unbelievable or what?)
What the rules say:
Where are these mythological 'illegal target zones'? Luckily the WFTDA has a list AND a picture.Hitting an opponent in the back of the torso, back of the legs, or back of the buttocks is prohibited. Hitting an opponent with a legal blocking zone into a legal target zone while positioned behind said opponent is not blocking to the back and is not necessarily illegal.
This is ably demonstrated by this picture:4.2.2 - Illegal Target Zones: For safety reasons, a Skater may not be hit in the following locations:
22.214.171.124 - Above the shoulders
126.96.36.199 - The back of the torso, back of the buttocks, or back of the thigh
188.8.131.52 - Below mid-thigh
As you can see, basically the whole butt (apart from bits at the side), the back and the back of the legs are prohibited.
No Impact/No Penalty
Ok, so incidental contact is probably not going to warrant a penalty. Same as all rules.5.1.1 - Any contact to the back of an opponent that forces the receiving opponent off balance, forward, and/or sideways, but does not cause any opponent to lose relative position or any teammate (or the initiator) to gain relative position.
Now, this is where things get a little bit weird. The wording of this seems to actually be a little bit contrary to the NI/NP section as there is a difference between 'relative position' and 'established position'.5.1.2 - Any contact to the back of an opponent that forces the receiving opponent out of their established position. This includes forcing an opponent down, out of bounds, or out of relative position.
From the glossary:
A Skater’s location, when in bounds and upright, in relation to other Skaters involved in the action. Relative position is said to be “gained” or “lost” if said location changes in a way that gives or loses some advantage (for example, one Skater passing another, or being knocked down, out of bounds, or out of play). Relative Position is only measured in the counter-clockwise direction.
So established position is where the skater is on track. Relative position is where the skater is on track IN RELATION to other skaters. Hopefully that makes sense.Established Position
Where a Skater is physically; an area of the track where the Skater has secured their place. Examples: up, in bounds, down, out of bounds, in play, and/or out of play.
That means that as long as the skater is not moved from where they are on track AND where they are in relation to other skaters, then it's probably not a penalty. Example of a penalty would be - a jammer pushing against a blocker's butt so that she goes out of play (she has lost her established position ie, being in play). Another would be a skater hitting another skater in the back of the thighs so that she falls. However, if a blocker back blocks another skater out of a wall (for example, moving her forward in front of two of her fellow blockers) this is *not* a penalty if no one immediately takes advantage of the space created by the moved blocker. Because, in relative position terms, she has GAINED relative position - there has been no loss of relative position for anyone, and the opposition has not gained from it. This is followed up by the following rule:
Note how it does not say "that causes the opponent to gain" relative position - in other words, you can back block the opposing jammer through your own wall and you probably won't get a penalty (there are no guarantees, obviously, I'd have to see it to call/not call it - if it's intentional you might get expelled.). Your team mates might hate you though.5.1.3 - Any contact to the back of an opponent that causes any opponent to lose relative position, or the initiator or any teammate to gain relative position.
Basically - you hit someone in an illegal target zone and the result is that they do one of the following, you will very much likely get a penalty:
*Fall (even if just on one knee)
*Go out of bounds
*Go out of play
*stumble so severely that an opposition player can get past (even though they don't fall, the result is a loss of relative position for them)
I'm sorry, but this rule always makes me think of this: https://youtu.be/mIWd3T1xjec?t=18The following egregious acts will be automatic game expulsions. Expulsions will be issued for a conscious and forceful attempt to block an opponent in the back egregiously, whether or not the action was successful.
5.1.4 - Negligent or reckless illegal contact to the back of an opponent, back of an opponent’s legs, or back of an opponent’s buttocks.
Basically, don't do it. It's dangerous. I've seen a few people get really hurt this way.
Now, I appreciate that the whole relative/established position bit was confusing, so ASK AWAY.