Denver Broncos safety Kareem Jackson returned from an NFL-imposed suspension on Sunday night and made nine tackles in a 21-20 victory over the Minnesota Vikings.

On Monday, the NFL suspended the former Alabama standout for four games without pay again for almost exactly the reason that it had previously. But his time, Jackson was not penalized during the game for the action the NFL deemed suspension-worthy.

The play in question occurred when Jackson hit Minnesota quarterback Josh Dobbs on the third snap of Sunday night’s game, resulting in a fumble. Denver recovered the football on the Vikings 30-yard line and got to keep it since no penalty was called.

But in a letter sent to Jackson, Jon Runyan, the NFL’s vice president of football operations, asserted Jackson had violated Rule 12, Section 2, Article 10 (a) of the NFL rulebook, which states: “It is a foul if a player lowers his head and makes forcible contact with his helmet against an opponent.”

Runyan wrote: “With 13:38 remaining in the first quarter, you were involved in a play that the league considers a serious violation of the playing rules. The video of the play shows that you lowered your head and made forcible contact to Vikings quarterback Josh Dobbs. You had an unobstructed path to your opponent, and the illegal contact could have been avoided.

“Illegal acts that are flagrant and jeopardize the safety of players will not be tolerated. The league will continue to stress enforcement of the rules that prohibit using your helmet to make forcible contact with your opponent. On the play in question, you lowered your head and delivered a forceful blow to the shoulder and head/neck area of an opponent when you had time and space to avoid such contact. You could have made contact with your opponent within the rules, yet you chose not to.”

On Oct. 23, the NFL suspended Jackson for four games for a hit in the Broncos’ 19-17 victory over the Green Bay Packers the previous day. On the third snap of the fourth quarter, Jackson brought down Packers tight end Luke Musgrave with what was judged a helmet-to-helmet hit at the end of an 18-yard reception. Jackson was penalized for unnecessary roughness and disqualified from further participation.

Runyan cited Rule 12, Section 2, Article 9 (b)(1) when he suspended Jackson that time. That rule states: “It is a foul if a player forcibly hits the defenseless player’s head or neck area with the helmet, face mask, forearm or shoulder, even if the initial contact is lower than the player’s neck, and regardless of whether the defensive player also uses his arms to tackle the defenseless player by encircling or grasping him.”

Jackson appealed his first four-game suspension to the hearing officers jointly appointed and compensated by the NFL and NFL Players Association to decide appeals of on-field player discipline, and Derrick Brooks reduced the suspension to two games.

Jackson can appeal his latest suspension, too. He stands to lose $558,889 in salary if the four-game ban stands.

Jackson was fined by the NFL four times for unnecessary roughness in the first six weeks of the 2023 season. Twice the fines stemmed from penalties called on the field.

The NFL fined Jackson $14,819 in Week 1, $19,669 in Week 2, $11,473 in Week 3 and $43,709 in Week 6.

In Denver’s 35-33 loss to Washington on Sept. 17, Jackson was penalized and ejected for a hit on Commanders tight end Logan Thomas on a touchdown reception with 1:47 left in the first half.

A first-round draft choice from Alabama’s 2009 BCS national-championship team, Jackson is in his 14th NFL season.

Among Alabama alumni, only Chris Mohr, Howard Cross and Cornelius Bennett have played in more NFL regular-season games than Jackson and only Bennett has started more games.

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Mark Inabinett is a sports reporter for Alabama Media Group. Follow him on Twitter at @AMarkG1.