Disclaimers are a normal part of advertising. Sellers use them to provide potential customers with useful information. Sellers also use disclaimers to protect themselves against disappointed customers, bad publicity and claims of harm. Researchers have found that sellers’ disclaimers are beneficial.

But what about disclaimers mandated by governments?

There is no fine print in the First Amendment to the Constitution; no conditions impinge on freedom of speech. Yet for nearly two-fifths of the Bill of Rights’ 221-year life, government lawmakers have restricted the speech of sellers. Moreover, courts have frequently accepted the lawmakers’ speech restrictions. In effect, lawmakers and judges have nullified the First Amendment based only on their judgments that the benefits outweigh the costs of speech restrictions.

In 2002, the U.S. Supreme Court decided not to hear a case about a Florida mandate that dentists advertising implant dentistry qualifications needed to include a disclaimer (Borgner et al. v. Florida Board of Dentistry et al.). In their dissent, Justices Thomas and Ginsburg stated, “If the disclaimer creates confusion, rather than eliminating it, the only possible constitutional justification for this speech regulation is defeated.”

As expert witnesses for a follow-on case, Ducoin v. Viamonte Ros, I helped to conduct an experiment as an answer to Justices Thomas and Ginsburg’s call for evidence on the effects of speech restrictions. Our fieldworkers showed two advertisements for dentists offering implant dentistry to 317 people, who were recruited in a Florida shopping mall. All subjects were shown an ad for a dentist who made no claim to have credentials for performing implant dentistry and another ad for a dentist certified by the American Academy of Implant Dentistry (AAID). Half of the subjects were shown a version of the credentialed dentist’s ad that included the Florida mandatory disclaimer, which stated that the American Dental Association did not recognize the AAID as “a bona fide specialty accrediting organization.”

Our fieldworkers asked the subjects which dentist they would recommend to a friend in need of implant dentistry services. The subjects exposed to the mandatory disclaimer were more likely to recommend the dentist without credentials. Moreover, the subjects who saw the disclaimer drew false and damaging inferences about the credentialed dentist. Women and less-educated subjects were particularly prone to be influenced by the disclaimer in these damaging ways. Our findings convinced the Florida Circuit Court judge that the disclaimer was unjustified.

Ours was not the only relevant study. Previously published experiments have shown that admonishments to change or avoid behaviors typically have effects opposite to the original intention. More specifically, all of the 18 experimental studies providing evidence relevant to mandatory disclaimers found that they increased confusion. In addition, the disclaimers were ineffective or harmful in all of the 15 studies that examined perceptions, attitudes or decisions.

Our findings were published in “Evidence on the Effects of Mandatory Disclaimers in Advertising” in a recent issue of the Journal of Public Policy & Marketing, along with commentaries. In our reply to the commentators, “Should We Put a Price on Free Speech?” we argue that there is another reason to support free speech—it is a basic right guaranteed by the Constitution.