After an Ohio grand jury decided on Monday (Dec. 28) not to indict Timothy Loehmann, the police officer who shot and killed 12-year-old Tamir Rice in Cleveland in 2014, the Twitterverse decided to ask Cleveland's favorite athlete (and probably favorite human of all time) to do something about it.

People on Twitter started using the hashtag #NoJusticeNoLebron to ask Lebron James to "lead a collective sit out until the DOJ imprisons the murderers of Tamir Rice." Some pointed out that prominent football players at the University of Missouri recently succeeded in making the school's president, who students accused of being racist, resign from his post by going on strike and refusing to play.

James has a history of speaking out against police violence and in support of the Black Lives Matter movement. When he was still playing for the Miami Heat in 2012, he famously led the team in a powerful statement of protest over the killing of 17-year-old Trayvon Martin. Trayvon was wearing a hoodie when he was gunned down while walking home from a 7-Eleven with a bag of Skittles and an iced tea.

Following a "Million Hoodie March" in New York, James posted a photo to Twitter of the Miami Heat with their hoods up with the hashtag #WeAreTrayvonMartin as a quiet reminder that because of racial bias, black men in hoodies -- even pro-athletes -- are often unjustly regarded as inherently menacing. James also wore sneakers emblazoned with the phrase, "R.I.P Trayvon Martin."

Earlier this month, after a grand jury in New York refused to indict the police officer who killed Eric Garner with a deadly chokehold, James and other players wore "I can't breathe" T-shirts before games in support of Eric Garner protests.

Although he hasn't commented specifically on Tamir Rice, when asked earlier this month whether police violence was "more troubling" to him because several high-profile incidents took place in Cleveland, James responded, "It doesn't matter, it's more troubling that it's happening in our country. This is our country, the land of the free, and we keep having these incidents happen ... our families are losing loved ones."

The NBA has also been touched by police violence more directly. Earlier this year, Atlanta Hawks player Thabo Sefolasha was wearing a hoodie when he was assaulted by police outside a New York City club and wound up with a broken leg. The New York Police Department pressed charges, claiming Sefolasha resisted arrest, but a jury has since exonerated him. The shooting guard is now suing the NYPD for $50 million for ending his season and robbing him of a possible title run. Sefolasha has publicly shared his story in order to speak out against police violence, saying that this was "an act of police brutality" that "could happen to anyone."

Even when the issues don't affect players so directly, there's a long history of professional athletes taking a stand for social justice. Muhammad Ali famously spoke out against the Vietnam war, and was even sentenced to jail time for fighting the draft. Olympic track star John Wesley Carlos used his bronze metal-moment to give a black power salute that rocked the world. There are many more examples like theirs.

Hall-of-fame "greatest football player ever" Jim Brown, who has a long history of speaking out about social justice issues (and incidentally also played for Cleveland) has applauded pro athletes and NBA players for weighing in.

“The thing is that, when you are a popular athlete, and you accept the money and the fame, and you become a front person for those who have the power," Brown has said. "And they say be like this guy and kids that are coming up say, well, be like him, I won’t protest against anything, I’ll accept everything, I’ll just try to be a great athlete and make a lot of money. So a culture dies when you do that. You’re doing a great injustice to young kids that are coming up, and I never wanted to be a representation of less than a man and have young kids coming up emulating me.”

In keeping with that spirit, NBA all-stars including Chris Paul, Carmelo Anthony and Steph Curry (but sadly, no LeBron) shared their thoughts about ending gun violence earlier this week in a PSA that got support from President Obama.

But does all of this mean that James is going to heed the Twitter's calls and go on strike to demand justice for Tamir? It's hard to hope for.

This definitely isn't the first time people on Twitter have rallied together to ask a celeb to leverage their status in support of a social issue. Back in August, activists used the hashtag #BeyBeAHero to ask Houston-native Beyonce to help stop the repeal of Houston's Equal Rights Housing Ordinance (HERO), which banned discrimination against LGBT people. Bey declined to weigh in, and ultimately HERO lost.

It isn't hard to see why celebs and pro-athletes would be afraid to set a precedent of doing something just because a bunch of people asked them to on Twitter -- even when the request involves an issue they care deeply about. But here's to hoping James -- and other pro-athletes and celebs -- will continue to use their platforms as a powerful tool for good.