Facebook user Daniel Ray Carter Jr was fired from his job as Deputy Sheriff of Hampton, Virginia, in 2009 after he 'liked' a page on the site representing a candidate who was challenging his boss, the Sheriff of Hampton B J Roberts, in an upcoming election.
Carter filed a lawsuit claiming that his First Amendment right to free speech as enshrined in the US constitution had been violated by the action.
After a court ruled that 'liking' something on Facebook does not warrant protection as no 'actual statements' are involved, Carter - backed by the American Civil Liberties Union (ACLU) - opted to escalate the case to the US Court of Appeals earlier this week.
Carter and the ACLU are concerned that if the ruling is upheld, it will set the worrying precedent that mouse click actions, such as 'liking' on Facebook or retweeting on Twitter, won't be protected under rules of free speech.
Facebook has also filed briefs to the court supporting Carter's claim that it is his constitutional right to express an opinion while on the social network or other websites.
According to Facebook, more than 3 billion 'likes' and comments are registered every day by its more than 950 million users.
In its submission to the court earlier this week, the ACLU said that 'liking' a political candidate was akin to placing a bumper sticker on your car - it is "telling the world about one's personal beliefs, interests and opinions".
"With 'one click of a button', an internet user can upload or view a video, donate money to a campaign, forward an email, sign a petition, send a pre-written letter to a politician, or do a myriad of other indisputably expressive activities," the ACLU said.
"The ease of these actions does not negate their expressive nature. Indeed, under the district court's reasoning, affixing a bumper sticker to your car, pinning a campaign pin to your shirt, or placing a sign on your lawn would be devoid of meaning absent further information, and therefore not entitled to constitutional protection because of the minimal effort these actions require. All of these acts are, of course, constitutionally protected."
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It added: "That many people today choose to convey what they like or which political candidates they support by "liking" a web page rather than by writing the actual words 'I like this web page' or 'I like this candidate' is immaterial.
"Whether someone presses a 'like' button to express those thoughts or presses the buttons on a keyboard to write out those words, the end result is the same: one is telling the world about one's personal beliefs, interests and opinions. That is exactly what the First Amendment protects, however that information is conveyed."
The case could have major ramifications for the future, particularly as actions on Facebook are increasingly having significant effects in 'real' life, reports The Washington Post.
In April, the US Marine Corps announced that it had discharged a sergeant who had used his Facebook page to criticise Barack Obama, including the alleged posting of an image of the president's head on a poster for the movie Jackass.
The American National Labour Relations Board also reported last autumn that it had seen the number of cases involving workers being fired for social media activity increase from zero to 100 over the past five years.