Here is a Ray Lutz “Forward Progress” post from August 29, 2008 (Edited for clarity)
The play missed most overall by officials is probably the block in the back. When I say missed I don’t mean that it isn’t called, I mean we call it incorrectly way too often. We rule a ton of good blocks as illegal blocks in the back.
Here is the rule from 2-5-2
ART. 2 … Blocking in the back is a block against an opponent when the initial contact is in the opponent’s back, inside the shoulders and below the helmet and above the waist, and not against a player who is a runner or pretending to be a runner.
APPROACH GUIDELINES
An important guideline is the approach angle of the blocker. If that angle is 45 degrees or less, there is no way the block can be illegal. If the approach angle reaches the 60-degree range, then the block becomes suspect.
Visualize this. You are driving a car, and you look out the side driver’s window, and you see a car coming that is going to broadside you. That block would be legal. It would have been legal even if you didn’t see it coming.
If, as the driver of the car, you must twist your neck way around and look out the back seat passenger window to see the block, or even look in the rear view mirror to see it, that block would probably be illegal.
The blocker who makes illegal contact in the block will be pursuing the player being blocked. We call them “chasers.”
Identify the “Bricks”
You must see the “initial contact” to rule on the block. I say you must see the approach. I say you must identify the “bricks,” the players in position to not only block, but block illegally. You cannot find bricks if you are looking at the ball carrier.
CONTACT GUIDELINE: Where is the back?
Inside the shoulders is a very important part of this definition. The shoulder is made up of the clavicle in the front and the scapula in the back. For the block to be illegal by rule, the contact must be inside the scapulas. In other words, the block must be on the “numbers.”
The numbers are a very important guideline in calling this foul. If at least one of the numbers on the back of the uniform of the player being blocked is covered by the blocker, the block is probably illegal. If both numbers are covered, it is a no-brainer.
POST CONTACT GUIDELINES: The way the player being blocked falls to the ground is another guideline. If he falls to the ground on his back or his side, the block is most likely legal. If, however, he falls onto the front of his body, the proverbial “face plant,” the block is undoubtedly illegal.
If the legs of the player being blocked “kick out” sideways toward the blocker, the block is probably legal. If the legs of the player being blocked kick backward, the block is likely to be an illegal block.
Quiz
Read the quiz stem and then choose the best answer. (Choose all that apply.)
4/5 from the K-10. While K34’s punt is in the air, K56 is flagged for an illegal blindside block against R40 at the K-20. R12 fair catches the punt at the K-30. R40 stands up, charges at K56, and shoves him to the ground.
- R40’s foul is unsportsmanlike conduct
- K56’s and R40’s fouls will offset
- Team R must decline the penalty for K56’s foul and enforce the penalty for R40’s foul to keep the ball
- Enforce the penalty for K56’s foul from the K-30
- Enforce the penalty for R40’s foul from the K-30
- Team R may choose to free kick the ball following penalty enforcement
Review Rules 6-5-4a, 10-2-5a, 10-4-2 EXCEPTION, 10-4-5b