Prior to last Friday’s preseason National Football League (NFL) game between the San Francisco 49ers and the Green Bay Packers, 49er quarterback Colin Kaepernick refused to stand during the playing of the national anthem to protest police killings of African Americans in the United States.

Kaepernick is a 28-year-old biracial man who was raised by the white parents who adopted him. His action was particularly courageous because the former Super Bowl starting quarterback is fighting to maintain his football career after losing his starting job last season. Drafted in 2011, he had been one of the most promising players in the NFL during his time under former coach Jim Harbaugh.

“I am not going to stand up to show pride in a flag for a country that oppresses black people and people of color,” Kaepernick told NFL Media in an interview after the game. “To me, this is bigger than football and it would be selfish on my part to look the other way. There are bodies in the street and people getting paid leave and getting away with murder.”

Kaepernick went on to add, “This is not something that I am going to run by anybody, I am not looking for approval. I have to stand up for people that are oppressed. ... If they take football away, my endorsements from me, I know that I stood up for what is right.”

After Sunday’s practice Kaepernick addressed the media reaffirming his position and that he will continue to sit during the playing of the national anthem before games until “there’s significant change and I feel like that flag represents what it’s supposed to represent in this country—is representing the way that it’s supposed to.”

When asked if the pending presidential election had anything to do with the timing of his actions, Kaepernick responded, “I mean, you have Hillary [Clinton] who’s called black teens or black kids super-predators. You have Donald Trump who’s openly racist. I mean, we have a presidential candidate who’s deleted emails and done things illegally and is a presidential candidate. That doesn’t make sense to me, because if that was any other person, you’d be in prison. So what is this country really standing for?”

While many of Kaepernick’s comments have been within the identity politics framework promoted by the Clinton campaign and such groups like Black Lives Matter that deliberately seek to conceal the class character of police violence, the athlete has nevertheless been subjected to rabid denunciations aimed at silencing any political dissent.

The media has regularly shown fans burning his jersey and highlighted the statements of more politically backward football players. TJ Yates, an injured quarterback of the Houston Texans, tweeted, “It blows my mind how many people hate the country they live in.” Matt Hasselbeck, former NFL quarterback and current ESPN analyst, tweeted, “Easy way to make sure you’re NOT the starting QB on opening day. #Sept. 11.”

These are not the sentiments of broad layers of the public who are angered by police killings and indifferent to or disturbed by the endless promotion of patriotism and militarism at professional sporting events.

Several players defended Kaepernick’s right to express his opposition. Russell Okung, an offensive guard with the Denver Broncos, stated, “Kaepernick is well within his rights to do what he did. I’m not saying I agree, but I do understand why he felt morally obligated in his acts.”

Kaepernick, who addressed his team on Sunday, has won the respect of his teammates, even from those that disagree with his position. Center Daniel Kilgore said, “When it came out, honestly, I took offense to it,” Kilgore said. “But after Kap stated his case and seeing where he comes from, I stand with Kap.”

While Kilgore said he disagreed with Kaepernick’s decision to sit, he said, “I stand with Kap when he says enough is enough against crime, violence, discrimination and racism.”

The National Football League has not, at least until now, taken any action against Kaepernick. The 49ers released a statement praising what the anthem represents but recognizing that Kaepernick’s boycott matched up with “such American principles as freedom of religion and freedom of expression.” Kaepernick’s coach, Chip Kelly, said he had no right to tell any player how to honor, or not honor, his country. The NFL responded by indicating that players are encouraged but not required to stand for the anthem.

Over the last number of years there have been increasing protests by athletes over police killings. In December 2014, St. Louis Rams pass receivers Tavon Austin, Chris Givens, Jared Cook, Kenny Britt and Stedman Bailey entered the Edward Jones football field using the “hands up, don’t shoot” gesture popularized by protests over the police murder of unarmed black teenager Michael Brown in Ferguson, Missouri. The players said they wanted to express their solidarity with the people of Ferguson, the St. Louis suburb that had been put under siege by police and National Guard troops.

Athletes have also spoken out against militarism and war. In May 2011, the day after Obama’s announcement of the killing of Osama bin Laden, Rashard Mendenhall, the 23-year-old star running back for the Pittsburgh Steelers football team, tweeted: “What kind of man celebrates death? It’s amazing how people can HATE a man they have never even heard speak. We’ve only heard one side.”

Mendenhall’s comments—which were bound up with his religious convictions and skepticism in the government’s version of the 9/11 events—were immediately seized upon for a rabid campaign accusing the football player of being disloyal and contemptuous of the 3,000 Americans killed by the terrorist attacks. The fraternity of cable television sportscasters—who, with few exceptions, generally appeal only to the base instincts of sports fans—demanded that the NFL block athletes from having access to Twitter and social networking sites.

Shortly afterwards, sports apparel maker Champion fired Mendenhall, who had recently signed a four-year contract and had been a sponsor with the company since his NFL career started in 2008.

In 2004, Toronto Blue Jays baseball player Carlos Delgado refused to take the field during the playing of “God Bless America” during the seventh inning stretch. The song became a tradition after the events of 9/11, but had since been ended at several MLB stadiums with some teams only playing it on weekends and holidays. Delgado, who was strongly against war, including the ones that were currently being waged in Iraq and Afghanistan, felt the playing of the song was a political stand in itself that went against his beliefs. No action was ever taken against Delgado.

During this year’s Major League All-Star game, the Canadian-based vocal quartet The Tenors sang the Canadian anthem (there is one Canadian team in the Major leagues) at San Diego’s Petco Park. During a solo, Remigio Pereira changed the words of O Canada from, “With glowing hearts we see the rise, the True North strong and free,” to “We’re all brothers and sisters, all lives matter to the great.”

Pereira also brandished a sign with the words “All Lives Matter,” inviting scorn from a plethora of prominent Canadians. The Tenors labeled him a “lone wolf” and kicked him out of the group. He later apologized.

Possibly the most well-known political demonstration during the performance of a national anthem at a sporting event occurred during the 1968 Olympics in Mexico, when two Black American athletes each raised a black-gloved fist during the Star-Spangled Banner at a medals ceremony.

John Carlos, the bronze medalist in the men’s 200-metre race, and Tommie Smith, the gold medalist, performed the Black Power salute while on the podium to shine a spotlight on racial inequality in the US.

They were booed and forced out of the games by the president of the International Olympic Committee at the time, Avery Brundage, and suspended from the national team. The third man on the podium, a white Australian named Peter Norman, was vilified by his home nation for wearing his Olympic Project For Human Rights (OPHR) badge in solidarity. The OPHR was an organization formed to protest racial segregation.

The ritual of playing the national anthem before major sporting events dates back to the 1918 World Series. The US had entered the war 17 months earlier, and in that time some 100,000 American soldiers had died. The war had strained the economy and the workforce, including baseball’s. The government began drafting major leaguers for military service that summer and ordered baseball to end the regular season by Labor Day. As a result, the 1918 Series was the lone October Classic played entirely in September.

Hence a tribute that began to “honoring” the victims of the slaughter of World War I has developed into today’s militaristic ritual of opening sporting events by playing the national anthem accompanied by military honor guards, enormous flags, and often climaxing with fighter jets performing flyovers as fireworks go off.

Professional sports teams were paid tens of millions of dollars between 2012 and 2015 by the Department of Defense for patriotic tributes at professional football, baseball, basketball, hockey and soccer games, according to a November 2015 report published by Republican Arizona Senators John McCain and Jeff Flake.

Kaepernick’s protest was an act of personal courage. His actions, like those who have engaged in similar acts in the past, must be defended against the right-wing promoters of nationalism, militarism and state repression of political dissent.