Go to almost any major website today, from Amazon.com and Uber.com to job boards and dating sites, and you will likely see user reviews on everything from the quality of a faucet to a potential mate’s sex appeal. But when does a highly charged opinion cross the line into libel and defamation?

That was the issue confronting the California Court of Appeal in Marin County in a recent decision (ZL Technologies v. Does 1-7 and Glassdoor, Inc.)

The case required the court to balance every American’s right to free speech, guaranteed by the First Amendment and California law, against the right to protect one’s good name and reputation against libel and defamation.

Many readers of the court’s decision may be surprised by its conclusion that one way to be protected against a defamation complaint is to make sure your review is crude, ungrammatical, illogical, juvenile, vituperative and offensive.

In other words, the dumber, angrier and less credible your review is, the safer you are.

The case involved a lawsuit filed by ZL Technologies, a Silicon Valley tech company, against Glassdoor Inc. and seven “John Doe” defendants. The Glassdoor.com site lists job openings. It also offers user-generated information and opinions about salaries, interviewing strategies, company culture and more.

ZL Technologies believed that the reviews posted anonymously by the John Doe defendants were libelous and defamatory.

One review said ZL had the “best product on the market,” but “management lacks the experience or focus to drive growth.” Another also lauded the product, but said, “if you like to engage with your job like it’s a bloodsport in a Roman Coliseum, you’ll love your job. Also, pay is 30%-50%  lower than industry standards in Silicon Valley.” The other reviews had a similar mix of positive and negative comments, some of them scathing.

ZL demanded that Glassdoor turn over the names of the anonymous reviewers so ZL could sue them individually for libel.

Glassdoor refused, saying the comments were shielded by both the United States and California constitutions.

It said the posted statements were “protected opinion, patently hyperbolic, not harmful to reputation. It also said that disclosing the reviewers’ identities would harm Glassdoor’s reputation among its users. The trial court agreed with Glassdoor and dismissed ZL’s lawsuit, whereupon ZL appealed.

As an indication of the significance of the issues involved, friend-of-the-court briefs supporting Glassdoor’s position were filed by Twitter and Public Citizen, a nonprofit free speech advocacy group.

The appellate ruling noted that “the use of a pseudonymous screen name offers a safe outlet for the user to experiment with novel ideas, express unorthodox political views, or criticize corporate or individual behavior without fear of intimidation or reprisal.”

But there are limits on what is allowable. The court noted that, “when vigorous criticism descends into defamation, constitutional protection is no longer available.” The reason:   "neither the intentional lie nor the careless error materially advances society’s interest in uninhibited, robust and wide-open debate on public issues.”

California’s appellate court, in the landmark Krinsky v. Doe case (159 Cal.App.4th 1154), had previously ruled that “corporate and individual targets of these online aspersions may seek redress by filing suits against their unknown detractors.” To serve their complaints, “plaintiffs may then seek disclosure of those detractors’ identities.”

In the ZL case, the appellate court explored at length how to determine when an online comment transitions from being a harmless diatribe by someone simply blowing off steam, to being a defamatory statement meant to be taken seriously – and therefore, in this case, intended to be harmful to ZL’s reputation.

“The court must put itself in the place of an average reader” when deciding if a statement is actionable.

A comment is not likely to be taken seriously, it said, if its language is hyperbolic, ungrammatical, satirical, vituperative, uses juvenile name-calling, and is short on specifics.

But if the review is factually specific and serious in tone, and the reviewer claims to have first-hand or specialized experience, a reader is likely to treat that as a credible assertion of fact – and, if defamatory, the comment is fair game for a lawsuit by the target of the criticism.

The appellate panel sent the case back to the trial court for reconsideration of ZL’s request for disclosure of the identities of the John Does.

So, if you are thinking about posting a nasty anonymous online review about a company or individual, remember:  make it dumb, crude and/or unbelievable, and perhaps you’ll stay out of court.

By M. Laurie Murphy