FORTUNE — Applying old laws to new technology can be tricky. Earlier this year, the blogosphere was buzzing about an unresolved lawsuit over who owns business-related Twitter followers, the employee or the company. Now comes a decision in the U.S. District Court for Eastern Virginia that tackled a different issue: Can an employee be sacked for liking something (or someone) on Facebook?
The facts in a nutshell: In Bland v. Roberts, Bobby Bland and four coworkers in the sheriff’s department in Hampton, Va., clicked the “like” button on the Facebook page of Jim Adams, who was running against their boss, Sheriff B.J. Roberts, in 2009. Roberts won, and promptly fired all five, citing budget constraints, unsatisfactory work performance, and a lack of “harmony and efficiency” in the office. But Bland and his cohort contended it was liking Adams’ Facebook page that got them canned.
Of course, openly supporting your boss’s opponent in a political campaign seems risky on the face of it, but leaving common sense aside, the case hinged on whether a Facebook “like” meets the standard of free speech as protected by the Constitution. The judge ruled that it doesn’t, adding, “In cases where courts have found that constitutional speech protections extended to Facebook posts, actual statements existed within the record” (emphasis is his).
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That’s fine as far as it goes, say legal scholars, but the act of liking something on Facebook may be far more of a statement than the judge apparently realized. “Judges in general do not really understand Facebook,” observes Eric Goldman, who teaches at Santa Clara University School of Law in Silicon Valley. He also directs the school’s High Tech Law Institute and writes a blog on high-tech legal issues.
“Clicking on ‘like’ is so easy — or what social media mavens call “frictionless” — that the implications may be overlooked even by the person doing the clicking,” Goldman points out. A few of those implications: When other people visit the page you’ve liked, you may appear publicly as someone who likes it and, depending on your privacy settings, your “like” may turn up in all your friends’ newsfeeds.
Your “like” may also appear on your profile page and, if you like a business or an ad, the sponsor may buy another ad that redisplays your like to your friends. You may also be automatically signed up for a barrage of further news, sales pitches, and other information about whatever it was you liked.
Goldman and other experts believe all that, taken together, is more than enough to add up to speech as First Amendment cases have generally defined it. “But you can’t blame the judge for not grasping all that liking entails,” Goldman adds. “Nowhere on the site is it really spelled out — and that ambiguity may be deliberate on Facebook’s part.”
One thing that’s not ambiguous at all: In the wake of Bland v. Roberts, if you’d like to keep your job, be very careful with what or whom you “like.”
Tell us about your most embarrassing digital work moments: Committed a work email faux pas? Disparage your boss in an instant message… to your boss? How’d you recover? Tell us your stories for our You Can’t Fire Everyone series. Email us at firstname.lastname@example.org. We’ll highlight the most interesting and instructional ones.