WASHINGTON — “Like” the First Amendment? Then prepare for a fight, as courts and employers figure out whether a simple click on Facebook deserves free speech protection.

It’s 21st-century technology meets an 18th-century Constitution, and the real-world implications are starting to erupt.

In rural Mississippi, two firefighters and a police officer are serving 30-day suspensions because they hit “like” on a controversial Facebook post.

In Virginia, a sheriff’s department employee said he was fired for “liking” a page sponsored by the sheriff’s political rival. One federal appellate court already is being asked to weigh in; others surely will follow.

“As we continue to develop new media and new means of expression, it is important to ensure that they are constitutionally protected,” Rebecca Glenberg, a lawyer with the American Civil Liberties Union of Virginia, said in an interview.

When users click “like” on a Facebook post, their names are displayed next to the post. They’re also visible to other users.

The Virginia-based 4th U.S. Circuit Court of Appeals is considering the case of Hampton, Va., sheriff’s department employees allegedly fired for using Facebook and other means to back their boss’s rival. One employee communicated the support by clicking “like.” Another wrote a Facebook post.

A trial judge concluded last April that “merely ’liking’ a Facebook page is insufficient speech to merit constitutional protection.” He said it wasn’t the kind of “substantive statement” that courts traditionally have protected.

The subsequent appeal is the first to consider whether a Facebook “like” falls under the First Amendment, Glenberg said.

Underscoring the case’s importance, the ACLU and Facebook have filed separate friend-of-the-court briefs urging free speech protections.

“I am not aware of any other instances of an employee being fired for ’liking’ something,” Glenberg said. “There is, however, a trend toward employers monitoring employees’ social media use, so the potential for this sort of thing is certainly there.”

The potential for conflict is so great, in part, because social media are so omnipresent. In its 26-page amicus brief, prepared by attorney Aaron Panner, Facebook - with 800 million users worldwide - says that “over 3 billion likes and comments” are posted daily.

In Columbus, Miss., for instance, city officials suspended firefighters Damon Estes and Erik Minga and police Officer Lance Luckey after the men “liked” a Facebook post by firefighter Brad Alexander. Alexander had written critically about the whereabouts of a woman whose 2-year-old child was hit by a car.

Alexander subsequently apologized and resigned. As first reported by the Columbus Dispatch newspaper, the Columbus City Council then voted 4-3 on Tuesday night to suspend the three public safety officers who’d “liked” Alexander’s posting.

“When you start talking about social media, it’s a new frontier,” Columbus City Councilman Kabir Karriem said Friday in a telephone interview.

Karriem, who voted against suspending the officers, said they could appeal their suspensions to the city’s Civil Service Commission.

For all their high-tech origins, Facebook posts appear to be the kind of speech the First Amendment envisioned; they consist, after all, of words and pictures.

Dana Mattingly, for instance, was working in December 2010 for the Saline County Circuit Clerk’s office, in eastern Arkansas, when she posted several sentences that voiced sympathy for workers whom the newly elected clerk had just fired. The clerk then fired her.

Mattingly sued, and a judge upheld her posts as protected speech.

“A public employer may not fire an employee for speech relating to a matter of public concern where that speech causes no disruption to the workplace,” U.S. District Judge J. Leon Holmes concluded.

Clicking “like,” though, might seem more akin to applause or a thumbs-up gesture than to traditional speech. It might even defy literal meaning altogether, as some click “like” simply to acknowledge that a Facebook post has been seen; others, to ensure continued access to related information.

Judges now must sort out the meaning of the site’s various icons and metaphors, a 21st-century puzzlement that our founders never could have envisioned.

Philadelphia-based U.S. District Judge Gene K. Pratter, for instance, briefly considered during a 2009 corporate dispute what it meant to be identified as a Facebook “friend.” Observing in a footnote that “friendships on Facebook may be as fleeting as the flick of a delete button,” Pratter said Facebook’s “selection of icons or labels offer no substance” that helped in resolving that particular dispute.

In its amicus brief in the Virginia case, Facebook said clicking “like” “generates statements and communicative imagery” on various other pages; some are the “21st-century equivalent of a front-yard campaign sign,” according to the brief.

The First Amendment does protect wordless expression. In 1984, notably, Gregory Lee Johnson set an American flag on fire in front of Dallas City Hall. He was convicted of violating a state law that prohibited desecrating the flag and was sentenced to a year in jail. In a 5-4 decision, the Supreme Court struck down the state law.

“The First Amendment literally forbids the abridgment only of ’speech,’ but we have long recognized that its protection does not end at the spoken or written word,” Justice William Brennan wrote in the 1989 decision.

ACLU attorneys note, as well, that even hard-to-understand expressions have been protected.

When the South Boston Allied War Veterans Council wanted to exclude gay marchers from a 1993 St. Patrick’s Day parade, the Supreme Court unanimously recognized that marching as a form of expression protected by the Constitution. Otherwise, the court reasoned, ambiguous expressions such as the “Jabberwocky verse of Lewis Carroll” would lie outside the First Amendment as well.

All of which could help shape what judges do with the Facebook “like.”

“A ’like’ might be only a tiny bit of speech,” said Andy Sellars, a staff attorney with the Harvard Law School-affiliated Digital Media Law Project, said, “but clicking a ’like’ is still a statement.”