The NFL released a statement Monday explaining the ending of the San Diego-Pittsburgh game.
After an instant replay review and crew conference, the on-field ruling of a touchdown was incorrectly reversed to no touchdown due to an illegal forward pass by San Diego.
There were three passes on the play. The first was a completed forward pass from San Diego's Philip Rivers to LaDainian Tomlinson. The second, from Tomlinson to Chris Chambers, was initially ruled a legal backward pass but then reversed in replay to an illegal forward pass. The third, from Chambers, was a legal backward pass that hit the ground and was returned for the touchdown by Pittsburgh's Polamalu.
The incorrect reversal of the on-field ruling of a touchdown was acknowledged immediately following the game by referee Scott Green in the pool report interview with a representative of the media.
If any forward pass, legal or illegal, hits the ground, the play is dead immediately. The officiating crew mistakenly determined that the backward pass that Polamalu legally recovered and returned for the touchdown was the pass that was reversed in replay to being forward and illegal. Therefore, the crew ruled that the ball was dead when it hit the ground and the play was over. (The actual illegal forward pass -- Tomlinson to Chambers -- did not hit the ground and therefore the play is allowed to continue.)
If the situation had been handled properly, the defense (Pittsburgh) would have declined the penalty for an illegal forward pass from Tomlinson to Chambers and taken the touchdown.
The rules relevant to this particular play are as follows...
Rule 8, Section 1, Article 1 (b) states "When any illegal forward pass is caught or intercepted, the ball may be advanced and the penalty declined." (page 49 of 2008 Official Playing Rules of the National Football League)
Rule 8, Section 1, Article 5 states "Any forward pass (legal or illegal) becomes incomplete and the ball is dead immediately if the pass strikes the ground or goes out of bounds." (page 50 of 2008 Official Playing Rules of the National Football League)
Rule 8, Section 4, Article 1 (b) states "A defensive player may catch a backward pass or recover it after the pass touches the ground and advance." (page 58 of 2008 Official Playing Rules of the National Football League)