In the complex labyrinth of NFL rules, contact to the head of a sliding quarterback is not necessarily a penalty.

That's the upshot after a sober, morning-after analysis of a hotly disputed decision Monday night at FedEx Field. Referee Walt Coleman declined to penalize Washington Redskins linebacker Trent Murphy for a hit to the helmet of Carolina Panthers quarterback Cam Newton, a non-call that was exacerbated by a taunting penalty on Newton and ultimately reignited the debate on whether Newton is treated fairly by NFL officials.

We won't resolve that argument today -- or maybe ever -- but I do think we can better understand why Newton didn't get the call in this particular situation. It begins with a point of emphasis the NFL established for the 2016 season, one that provided a rare concession to defensive players who are typically the target of all safety-related rules.

When a player slides feet first, he is by definition giving himself up. The ball is declared dead at the moment the slide begins. Defenders must consider that player, whether he is a quarterback or not, to be down by contact.

It gets difficult to adjudicate, however, when the slide begins after a defender has committed to a tackle attempt. The defensive player can't always stop, redirect or lessen the force of a blow in those situations. So this season, the NFL distributed a point of emphasis encouraging the slide to begin before contact is "imminent."

The full wording: "Runners [especially quarterbacks] who want the protection afforded sliding players must make every effort to slide feet-first before contact is imminent. If a runner starts his slide when contact is imminent, a defender is not prohibited from making forcible contact, as long as it is below the head/neck area."

That point of emphasis reinforced a note in the NFL rulebook that any player who "waits until the last moment to begin his slide" will put himself "in jeopardy of being contacted" legally.

Now let's go to the play Monday night. Newton began his slide when Murphy was about a step away. Coleman told a pool reporter that he ruled Newton had in fact started his slide late, a call the NFL leaves up to the judgment of the on-field officials.

That was part of Coleman's decision not to throw the flag. The other was the level of contact Murphy made with Newton's helmet. As the NFL noted in its point of emphasis, a defender can make forcible contact with a player who slides late -- as long as it's not to the head or neck area.

But the key is not whether there is contact with the head or neck area. It's whether that contact is "forcible."

I thought it was forcible when watching the game live and reacted as such. But watching it again at regular speed, which is important given that it was not a reviewable play, it appears Murphy first dove in an attempt to tackle Newton. As a result of the slide, Murphy flew over the top. His arm and/or chest hit the top of Newton's helmet.

In Coleman's judgment, the contact was not forcible.

"What we ruled," Coleman said in the pool report, "was that he slid late but that there was no forcible contact with the head -- that he just went over the top."

You might feel that the subjective nature of the interpretation provided Coleman postgame cover, but that is the way the rules are written and structured. The NFL doesn't want to penalize defensive players for mild and unavoidable contact any more than it wants quarterbacks subjected to unnecessary hits. The league's answer this season was to implore players to start their slides as early as possible, even if it means giving up a few yards, to ensure protection.

How that happens in real time is always going to be a matter of judgment. You can agree or disagree with Coleman in this case, but his decision was not nearly as obvious as it seemed in the emotion of the moment. So it goes.