(CNN) -- When Baltimore Ravens linebacker Brendon Ayanbadejo spoke out in August in favor of a Maryland ballot initiative that would legalize gay marriage, state Delegate Emmett C. Burns Jr. wrote a letter to Ravens owner, Steve Bisciotti saying that many football fans are "opposed to such a view" and suggesting that Bisciotti "inhibit such expressions" from his employee.
Ayanbadejo, one of the first pro athletes to publicly support gay marriage, saw Burns' efforts to stifle him as a violation of his First Amendment rights.
On September 7, Minnesota Vikings punter Chris Kluwe's penned a scathing response to Burns, stating, among other things: "I can assure you that gay people getting married will have zero effect on your life. They won't come into your house and steal your children. They won't magically turn you into a lustful c**kmonster."
In an interview with CNN's Poppy Harlow, Kluwe attributed the "lustful c**kmonster" bit to the fact that he developed a talent for coming up with attention-grabbing message board postings after growing up playing a lot of online video games.
"If you can't make a point that sticks in someone's mind," Kluwe explained, "most people probably won't really listen to you. So I developed a writing style that combined logical presentation of facts with hopefully some pretty hilarious insults."
Colorful language aside, Kluwe was trying to make a serious point. He hoped that calling Burns out would spark a genuine conversation about the issues highlighted in the letter.
Professional athletes, on the whole, aren't as outspoken as Kluwe when it comes to gay marriage and other hot-button issues. For the most part, they keep low profiles because they don't want to upset fans, risk endorsement deals or disappoint their coaches.
Jackie Robinson, the first black man to play in the majors since the 1800s, desegregated Major League Baseball in 1947 when he joined the Brooklyn Dodgers.
Robinson let his talent speak for itself, playing in six World Series with the Dodgers, until his playing career was over and he became an advocate for civil rights. Recognized as a hero of the era, Robinson is the only player ever to have his jersey number -- 42 -- retired across the board by every Major League team.
In 1966, when he became eligible for the draft during the Vietnam War, boxer Muhammad Ali declared himself a conscientious objector. That same year, the heavyweight champion also delivered the "Black is Best" speech to 4,000 students at Howard University upon being invited to speak by the campus protest group Black Power Committee.
For refusing to enlist, Ali was arrested, fined and stripped of his title, and for more than three years he could not box in any state in the U.S. In 1967, Ali was convicted of violating United States Selective Service laws by refusing to be drafted.
As public opposition to the war grew, Ali delivered speeches across the country, at one point asking, "Why should they ask me to put on a uniform and go 10,000 miles from home and drop bombs and bullets on brown people in Vietnam while so-called negro people in Louisville are treated like dogs and denied simple human rights?"
Ali's conviction was overturned by the Supreme Court in 1971.
The outspoken Alis, however, were few and far between.
In 1990, for example, Michael Jordan declined to endorse Democratic North Carolina Senate candidate Harvey Gantt, saying "Republicans buy shoes, too."
Times have changed, and this past summer, Jordan helped President Barack Obama's re-election campaign net $3 million at a $20,000-a-plate fundraising dinner.
While the majority of professional athletes today still adopt a laissez-faire attitude toward taking a stand on controversial issues, the tide is slowly turning.
Cleveland Browns linebacker Scott Fujita, a longtime advocate for NFL player safety, publicly accused Commissioner Roger Goodell this month of abusing his power by not being more vigilant about health and safety issues concerning players.
"He failed to acknowledge a link between concussions (and) post-career brain disease," Fujita said in a statement, "pushed for an 18-game regular season, committed to a full season of Thursday night games, has continually challenged players' rights to file workers' compensation claims for on-the-job injuries, and he employed incompetent replacement officials for the start of the 2012 season. His actions or lack thereof are, by the league's own definition, 'conduct detrimental.' "
Goodell maintained that Fujita, a former New Orleans Saints team captain, should have done more to stop players from participating in a team bounty program. That scandal involved several Saints defensive players who were discovered to have secretly managed a pool of money from which bonuses were awarded to players who injured opponents between 2009 and 2011.
Goodell suspended Fujita for three games but reduced that suspension to one, acknowledging that Fujita did not participate in Bountygate.
In Minnesota, as residents prepare to vote on an amendment to ban gay marriage, Kluwe remains outspoken.
"It would be great if Minnesota could show America that this state treats people the right way and knows that gay people contribute just as much to society as straight people," Kluwe said.
Although he himself is not a homosexual, Kluwe posed for the November cover of Out magazine. He noted that historically -- though most sports figures are reluctant to do so -- it has often been professional athletes who have brought about awareness of issues like gay marriage and civil rights.
"When sports gets on board with a civil issue, then that issue is rapidly resolved in the next, you know, 10, 15 years," he said. "Sports speaks to a large segment of the population, and when kids look at athletes as role models, they say, 'OK, hey, these guys are saying it's OK if you're gay, it's OK to have same-sex marriage.' "
Kluwe maintains that, despite his outspokenness, he has no plans to become a politician after his playing days are over. He hopes that one day, it won't be necessary for him to defend the issue of gay marriage.
"It shouldn't be news when someone speaks out for equality," he said. "It should be news when someone speaks out against equality."