What’s the NFL’s forward progress rule?

We see players ruled down by forward progress in every NFL game. Most of the time, it’s routine, but sometimes those calls mean that what looks like an obvious fumble isn’t called one.

But what does the rule actually mean?

Forward progress showed up in Spalding’s Official Foot Ball Guide for 1906, along with the legalization of the forward pass, which to that point had been considered a trick play. The forward progress rule reads:

Referee shall blow his whistle or declare the ball dead: ... Whenever he is so held that his forward progress has been stopped.

Here’s what the NFL’s rules say about it now:

The Forward Progress of a runner or airborne receiver is the point at which his advance toward his opponent’s goal ends and is the spot at which the ball is declared dead by rule, irrespective of the runner or receiver being pushed or carried backward by an opponent.

It’s pretty self-explanatory on the surface. The play is over when the ball carrier’s forward progress is stopped. But like the rest of the rule book, this one has some inherent flaws.

What happens when forward progress is called? Two things happen: The play is over, and the ball is dead. The line of scrimmage is marked at the point of the ball that is closest to the opponent’s end zone when the whistle is blown.

Deciding when to call forward progress is just a judgment call for officials. Typically, if a ball carrier’s legs are still moving and he’s still trying to advance the ball, they aren’t expected to blow the whistle until it’s clear there’s no more hope for forward momentum.

Why is it a rule? This rule exists in part to preserve fairness, and in part to protect players. Without the forward progress rule, a player could get a first down, but if the defense is able to stand him up and push him backward, it would overturn the first down.

The longer defenders are fighting to bring down an offensive player, the greater the chance of injury to any one of them. Blowing a play dead when forward progress is done reduces those chances a bit.

What’s the downside? We saw the Chiefs get burned by this rule twice against the Titans in the 2018 Wild Card Round. Forward progress can get tricky when there’s a fumble involved.

Marcus Mariota took a sack from Chiefs linebacker Derrick Johnson, and Mariota clearly fumbled the ball in the process. The Chiefs recovered, but it didn’t matter. Officials had blown the play dead, ruling Mariota down by forward progress.

The problem with this particular call is that Mariota didn’t actually move forward. He drops back, scans for an open receiver, and gets lit up and drops the ball. But since forward progress is purely a judgment call, the play wasn’t reviewable.

The refs weren’t done. After a Titans touchdown with just over six minutes to play that gave Tennessee a 22-21 lead over the Chiefs, Kansas City shut down a two-point conversion attempt by sacking Mariota. Mariota went backward — never forward — and fumbled the ball when he was taken to the ground. Chiefs linebacker Frank Zombo snatched it up and ran it into the end zone. So the Chiefs scored two points, right?

Wrong. Officials ruled once again, controversially, that Mariota was down by forward progress on a play that would have given the Chiefs a one-point lead and potentially a win.

A forward progress call wiped out what looked like a Joe Flacco fumble when the Ravens faced the Patriots in 2016. But Flacco was actually moving forward when his progress was stopped. So when he was driven back and lost the ball, that ball was already dead.

The forward progress rule itself is pretty simple. But identifying what forward progress is, exactly, is about as subjective as figuring out what is and is not a catch.