NEW YORK (Reuters) – A New York City dentist is being sued by a patient who says he is being fined $100 a day for posting negative reviews of his treatment on two consumer websites, according to the lawsuit filed this week.

Robert Lee was compelled to sign a privacy agreement before the dentist, Stacy Makhnevich, would treat a painful infected cavity in his tooth in November 2010, said the class-action suit filed on Tuesday in Manhattan federal court.

After filling the tooth, the dentist sent Lee a bill for $4,766, which he paid, and refused to send copies of his records to submit to his insurance company for reimbursement, it said.

In response, Lee posted a review on in August saying: “Avoid at all cost!”

“Scamming their customers!” he added. He posted similar comments on DoctorBase, a patient feedback website, the suit said.

The dentist began sending Lee invoices charging him $100 for each day the review was online, along with a notice threatening a lawsuit for breaching the privacy agreement, it said.

The dentist also sent legal notices to Yelp and DoctorBase insisting they remove the comments, the lawsuit said.

“Contracts like this suppress truthful speech,” Paul Alan Levy, an attorney for Lee, said on Thursday. He said it was part of a growing trend of businesses “abusing” intellectual property laws to suppress consumer criticism.

Makhnevich, who has an office in Manhattan’s Chrysler Building, did not return calls seeking comment.

The agreement Lee signed says he would not publish comments about Makhnevich’s work and would assign the copyright of any commentary he did make to her, the lawsuit said.

Lee said in the lawsuit he was dubious about signing it but did so because his tooth was causing him intense pain.

The lawsuit calls the privacy agreement misleading, a breach of medical ethics and not valid under state law. It also says posting commentary on a website such as Yelp is legally protected speech and considered “fair use” under copyright laws.

In the suit, Lee asks that the privacy agreement he and other patients signed be declared null and void and that Makhnevich be barred from presenting such agreements to future patients.

Lee is also seeking the cost of his treatment in damages.

The agreement was supplied to Makhnevich by Medical Justice, an organization based in Greensboro, North Carolina, that offers legal advice and services to physicians.

Ars Technica, a technology news website, reported on Wednesday that Medical Justice said it would “retire” the agreements and advise clients not to use them in light of the lawsuit.

Medical Justice did not respond to a request for comment.

Yelp users have rallied behind Lee. Dozens of negative reviews have been posted since the lawsuit was filed, many of them criticizing what they say is unethical censorship.