The 12 biggest controversies in the NFL's 100-year history

In 2016, Colin Kaepernick refused to stand during the National Anthem, beginning a league-wide protest.

From 2016 to 2018, NFL players from all 32 teams protested the anthem due to police brutality, racial inequality, and other controversies surrounding politics. The action led to dropped ratings and criticism from fans and President Donald Trump, causing the NFL to introduce an anthem policy, which was later halted before the 2018 season.

Read more: Colin Kaepernick posted a video saying he has been 'denied work for 889 days' and still wants to play in the NFL

The Immaculate Reception is one of the most famous plays in football that occurred on December 23, 1972. The Pittsburgh Steelers trailed the Oakland Raiders in the last 30 seconds of the game.

Steelers' quarterback Terry Bradshaw's pass was deflected either off a Raiders defender or the hands of John Fuqua and caught by Steelers' fullback Franco Harris. He then ran the ball in for the game-winning touchdown, giving the Steelers a 13-7 victory.

The controversy of the play is still unresolved, as many argued that the ball only touched Fuqua or that it hit the ground before Harris caught it. Either would make it an incomplete pass based on rules at the time.

During the Dallas Cowboys 2014 NFL playoff game against the Green Bay Packers, referees ruled that wide receiver Dez Bryant never made a "football move" before he lost possession of the ball after a remarkable catch.

If ruled complete, the Cowboys would have been at the Packers 1-yard line, trailing 26-21. Many disagreed with the call.

In 2018, the NFL competition committee ruled that the play should have been called a catch.

During the AFC Championship Game of the 2014-15 NFL playoffs, allegations arose that Patriots' quarterback Tom Brady ordered the deliberate deflation of footballs used in the team's victory against the Indianapolis Colts.

Brady was suspended for four games – effective for the 2016 regular season after appeals – and the team lost two draft picks along with a $1 million fine.

The controversy prompted the NFL to change its game ball procedures.

Read more: A 10-year-old boy won a science fair with a project concluding that Tom Brady is a cheater

During the 2012 NFL referee lockout, the NFL saw another officiating blunder on September 24. Trailing the Green Bay Packers 12-7 and heading into the final play, Seattle Seahawks' quarterback Russell Wilson threw a Hail Mary pass into the end zone.

Wide receiver Golden Tate and Packers' defender M. D. Jennings each got their hands on the ball as they attempted to gain possession. The officials gave separate signals of touchdown and touchback. After review, it was ruled that the players had simultaneous possession, giving the Seahawks a game-winning touchdown.

The controversial ending resulted in criticism over the quality of officiating by replacement officials during the 2012 NFL referee lockout.

In March 2014, Ray Rice was indicted by a grand jury on third-degree aggravated assault of his fiancée (now wife) Janay Palmer. Rice was suspended for the first two games of the 2014 NFL season in July 2014.

After full footage was released by TMZ, which showed Rice punching Palmer and knocking her out, Rice was released by the Ravens and indefinitely suspended from the league.

NFL Commissioner Roger Goodell said that he "didn't get it right" in deciding Rice's punishment and the incident caused the NFL to change its domestic violence policy, calling for a six-game suspension for a first offense and a lifetime ban for a second.

On March 28, 1984, former Baltimore Colts' owner Robert Irsay moved the team to Indianapolis in the middle of the night without any public announcement.

Irsay was in negotiations with the city of Baltimore to pay for renovations to Memorial Stadium. When the talks took a negative turn, the Maryland legislature passed a law allowing the city of Baltimore to seize the Colts from Irsay on March 28.

Irsay quickly took a deal from the city of Indianapolis and moved the team before anyone knew, stunning fans.

The 2001 AFC Divisional Playoff game between the New England Patriots and Oakland Raiders became known as the Tuck-Rule Game because of a controversial game-changing play.

Raiders' cornerback Charles Woodson sacked Tom Brady, which appeared to cause a fumble that was recovered by Raiders' Greg Biekert. Officials reviewed the play and determined that although Brady seemed to attempt to "tuck" the ball back into his body, it was an incomplete pass and not a fumble under NFL rules at the time.

Had the play been ruled a fumble, Oakland most likely would have secured the victory. However, the Patriots were able to send the game into overtime, where they won on a field goal. The Patriots went on to win Super Bowl XXXVI and began the Brady-Belichick era.

The New Orleans Saints were found guilty of paying out bonuses, or "bounties," for injuring opposing players from 2009 to 2011 in an incident nicknamed "Bountygate."

Defensive coordinator Gregg Williams was suspended indefinitely (overturned the following year), head coach Sean Payton was suspended for the entire 2012 season, and assistant head coach Joe Vitt was suspended for the first six games of the 2012 season.

The Saints organization was fined $500,000 and forced to forfeit second-round draft selections in 2012 and 2013.

Read more: NFL Commissioner Roger Goodell Explains The Saints' Severe Punishments

The Washington Redskins have been the subject of controversy and public scrutiny for decades because of their name and logo. The Native American community for many years has claimed the team "redskin" to be derogatory towards the group.

While activists have continued their fight, there has still been no change to the team's name or logo.

Read more: Former Washington Redskins defensive tackle calls the team's logo racist after signing with the Giants

During the 2019 NFC Championship Game, the Los Angeles Rams beat the New Orleans Saints, 26-23, in overtime after a crucial missed call by the referees.

With 1:48 left in the game, Drew Brees threw a pass to the sidelines to Tommylee Lewis, who was hit by Rams' defensive back Nickell Robey-Coleman in midair before he could get the ball. The referees did not call the pass interference call, although to many it looked obvious.

The Saints settled for a field goal, which was later tied by the Rams, who won in overtime. The NFL later admitted to missing the call.