Defensive players constantly try to pressure the quarterback on passing plays to cause an errant pass, force a fumble, or get a sack.
They run at full speed in pursuit of quarterbacks, which often ends up in a high-impact collision.
Many of these collisions are completely legal, as contact is all part of the game of football.
However, there are instances in which defensive players break the rules of the game and commit what's called a "Roughing the Passer" penalty.
This penalty is one of the most detrimental to defenses, as it can completely turn the game around.
What might have been a turnover or incomplete pass can turn into a huge gain for the offense with one simple penalty.
The problem is that the "Roughing the Passer" penalty isn't very easy to understand.
In addition, it's up to the referee's interpretation whether to call a "Roughing the Passer" penalty or not.
Let's take a closer look at some of the details.
Why the Penalty is in Place
The quarterback is one of the most important positions in football.
However, it is also one that puts players in a very vulnerable position.
Quarterbacks often stand still (or move slowly), looking for an open receiver, while the big, bulking defenders hunt them down.
They take a lot of hits during a football game, and some of these hits have a high likelihood of causing injury.
To try and clamp down on the potential for these injuries, football leagues created the "Roughing the Passer" rule.
The rule aims to dissuade defensive players from "teeing off" on quarterbacks with no regard for their health or safety.
It's a huge penalty as it results in a 15-yard penalty on the defense and an automatic first down for the offense.
"Roughing the Passer" penalties will also negate whatever play happened before the penalty.
For instance, if the defense intercepts a pass but are also called for a "Roughing the Passer" penalty, the interception is then cancelled.
The offense will gain 15 yards from the line of scrimmage and get a first down.
What Constitutes a Roughing the Passer Penalty
If the referee determines that a defender makes "unnecessarily rough" contact with the quarterback, they call a "Roughing the Passer" penalty.
The infraction can occur when the quarterback (or other player attempting a pass) has the ball still or has already released it.
Defensive players have to recognize when the ball is out of the quarterback's hands, and they must refrain from making unnecessary contact with the quarterback at this point.
Sometimes, contact is unavoidable due to the speed of the game, and that's OK - it just can't be rough contact, as determined by the ref.
The contact also can't come significantly after the quarterback has released the ball.
Defensive players also can't make moves that are "overly forceful."
This would include driving the quarterback hard into the ground or lifting him up into the air before tackling him.
These two examples would also merit a "Roughing the Passer" penalty.
Defensive players aren't off the hook when they go for a sack, either. By rule, they may NOT put all their weight on the quarterback when they go for the sack.
Defenders must try to break their fall to avoid causing serious injury to the quarterback.
As with all other hits in football now, too, defensive players can't hit the quarterback in the head or below the knees.
Either of these things would result in a "Roughing the Passer" penalty, too.
The "Roughing the Passer" penalty can be one of the more controversial calls in football today.
This is because it's up to a lot of interpretation as to what is an infraction and what is legal.
With the game of football being so fast, it can be hard to dictate what contact defenders could avoid and what they simply couldn't.
The leagues placed the rule to protect quarterbacks -- who are often in very vulnerable positions as they attempt passes.
Coaches need to educate their players on what the "Roughing the Passer" penalty is, and how to avoid it.
The penalty can be devastating to defenses, so avoiding it at all costs is vital.