Substitution rule ?

I have seen QB substitutions where they say the QB can not return to the game.   Anyone familiar with this ?

The third quarterback rule was a rule in the [You must be registered and logged in to see this link.] that governed the use of a third [You must be registered and logged in to see this link.] in addition to the [You must be registered and logged in to see this link.] and the [You must be registered and logged in to see this link.]. The rule was abolished for the 2011 season, when the NFL increased the roster size to allow 46 players to dress for a game.
The third quarterback did not count towards the team's 45-man [You must be registered and logged in to see this link.]. If the third quarterback entered the game at any [You must be registered and logged in to see this link.] during any of the first three quarters, the starter and backup became ineligible to play for the rest of the game; the third quarterback could have entered the game in the fourth quarter while preserving the eligibility of the starter and backup.
The full text of the rule was:

Teams will be permitted an Active List of 45 players and an Inactive List of eight players for each regular-season and postseason game. Provided, that if a club has two quarterbacks on its 45-player Active List, a third quarterback from its Inactive List is permitted to dress for the game, but if he enters the game during the first three quarters, the other two quarterbacks are thereafter prohibited from playing.

Although it is not specifically indicated, the NFL had interpreted its rule to mean that in order to designate a third quarterback, the two on the active roster must both be "bona fide" quarterbacks, not other position players merely designated as quarterbacks.

History[[You must be registered and logged in to see this link.]]

The third quarterback rule was instituted for the [You must be registered and logged in to see this link.] in reaction to a [You must be registered and logged in to see this link.] game between the [You must be registered and logged in to see this link.] and [You must be registered and logged in to see this link.]. In that game—sometimes called "[You must be registered and logged in to see this link.]"—Redskins lost both starting quarterback [You must be registered and logged in to see this link.] and backup [You must be registered and logged in to see this link.] to injuries. Without a third quarterback on their active roster, Washington had to either use a different player for that position or [You must be registered and logged in to see this link.] the game. [You must be registered and logged in to see this link.], a [You must be registered and logged in to see this link.] who played quarterback in college, completed the game in the quarterback position. The Redskins lost to the Eagles, 28-14.
The rule was abolished for the 2011 season. There is now no third quarterback exception and the active roster has been increased from 45 to 46.^{[You must be registered and logged in to see this link.]}

Notable games[[You must be registered and logged in to see this link.]]

In the [You must be registered and logged in to see this link.] [You must be registered and logged in to see this link.] between the [You must be registered and logged in to see this link.] and [You must be registered and logged in to see this link.], the rule was triggered with 57 seconds left in the third quarter. The Bears' starting quarterback, [You must be registered and logged in to see this link.], suffered from an [You must be registered and logged in to see this link.] sprain just after halftime. His replacement, [You must be registered and logged in to see this link.], was pulled after throwing four poor passes including two near [You must be registered and logged in to see this link.]. When [You must be registered and logged in to see this link.], the Bears' designated third quarterback entered the game before the fourth quarter, it meant that the Bears could not return either Cutler or Collins to the field the rest of the game. The Packers won the game, 21-14.

I knew I came to the right place for an answer.


Thanks Guys !