Businesses that have filed suit against consumers for posting negative reviews are now being highlighted by Yelp.

A pop-up box appears on the page of companies that have taken action against customers, reading: "Consumer Alert: Questionable Legal Threats. This business may be trying to abuse the legal system in an effort to stifle free speech, including issuing questionable legal threats against reviewers. As a reminder, reviewers who share their experiences have a First Amendment right to express their opinions on Yelp."

Consumers who visit the Yelp page for a Manhattan dentist who sued five different patients in the last four years over negative reviews now see the message, as do those who visit the page for a Texas pet sitter and Superior Moving & Storage in Florida. Prestigious Pets filed a $1 million complaint against a couple that posted a review saying the company overfed their pet goldfish while the Pompano Beach moving company took legal action after a consumer review awarded just one star.

Yelp decided to post the warnings in an effort to level the playing field. "Consumers don't necessarily know that these threats are sometimes empty or meritless (and often both!), so the threat of legal action is enough to scare them into silence," Yelp Senior Vice President Vince Sollitto wrote in a blog post announcing the addition of the alerts. He noted that the company was founded on principles of consumer free speech. "We don't think that's right."

Congress is currently considering legislation that would ban companies from using non-disparagement clauses prohibiting negative reviews and would ban the assignment of a copyright interest in a consumer review, two tactics used by businesses as the basis for lawsuits over negative reviews. The Consumer Review Fairness Act, H.R. 5111, was reintroduced in the House of Representatives after failing to pass last year.

To read the Yelp blog post about the consumer warnings, click here.

Why it matters: Yelp's new consumer warning also puts businesses on notice that the use of non-disparagement clauses or assignment of copyright interest with regard to online reviews is frowned upon by the site.