NFL: Chicago Bears at Houston Texans
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The NFL announced this offseason that it was banning the hip-drop tackle. The new rule states that this form of takedown is now a penalty, and will cost the defense 15 yards plus an automatic first down. However, 31 games into the season, the officials have done a poor job of upholding this rule.

The latest victim of the hip-drop was Houston Texans running back Joe Mixon, who will now get an MRI on Monday to determine the extent of his ankle injury, according to NFL Media.

Mixon immediately left the game and was officially listed as questionable to return with an ankle injury. He did return in the fourth quarter. Following the game, however, Mixon sounded off about the lack of enforcement.

"The NFL and NFLPA made it a rule and an emphasis for a reason," he wrote on Twitter. "Time to put your money where your mouth is."

Check out what happened, here:

"Joe got rolled up. The guy's weight definitely came down on his ankle," Texans head coach DeMeco Ryans said Monday. "Didn't look good from my view. We'll evaluate Joe throughout the week. Hopefully he's okay. Have to see the film and see if it was really a hip-drop tackle."

Several hip-drop tackles have been spotted in games over the first two weeks of the season, but yellow handkerchiefs have remained in the zebras' pockets. In fact, sources told CBS Sports NFL insider Jonathan Jones the league identified two hip-drop tackles that should have been called as penalties in Week 1.

While Bears linebacker T.J. Edwards was also not penalized for his actions, it sounds like the league still could fine him for this tackle. If you were curious, here's how the NFL defines the now illegal hip-drop tackle:

It is a foul if a player uses the following technique to bring a runner to the ground: (a) grabs the runner with both hands or wraps the runner with both arms; and (b) unweights himself by swiveling and dropping his hips and/or lower body, landing on and trapping the runner's leg(s) at or below the knee.