One of the defining trends of constitutional law in the past hundred years has been the growth of robust protection for free speech. It is now widely accepted that the First Amendment extends far beyond the protection of political speech to include all manner of expression. Today just about any law that burdens a class of speakers based on the content of their speech is subject to the most stringent level of judicial review — strict scrutiny — and is likely to be invalidated.

All of which should have set off alarm bells when the U.S. Court of Appeals for the 11th Circuit boldly declared last March that the regulation of “professionals’…direct, personalized speech with clients” received no First Amendment scrutiny whatsoever.

Fortunately, that aberrant holding may not stand much longer. This Friday, the U.S. Supreme Court will meet to decide whether to review the 11th Circuit’s ruling. If it takes the case — Locke v. Shore — it will be the Court’s first opportunity in 25 years to provide much-needed guidance on the First Amendment status of “occupational speech,” a murky area of the law that has grown increasingly important as more and more people earn their living by selling their speech.

Locke v. Shore is a challenge to a Florida law that requires interior designers to be licensed by the government before they may work in a commercial setting. The plaintiffs are three interior designers and the National Federation of Independent Business, some of whose members wish to engage in speech that Florida has broadly defined as the “practice of interior design.”

Florida is one of only three states in the nation to license the practice of interior design, and the burdens Florida’s law imposes on would-be designers are extraordinary, particularly in light of the fact that 47 states see no need to license them and have had no problems as a result. Acquiring an interior design license takes years and can cost tens of thousands of dollars. To be eligible for licensure, an applicant must first complete a combined six years of post-secondary education and apprenticeship under a state-licensed interior designer and pass a state-mandated exam administered by a private testing body.

Viewed through a First Amendment lens, the law is clearly unconstitutional. Virtually everything an interior designer does is speech, from consulting with clients regarding their personal goals and tastes, to drawing up space plans, to offering advice about the selection and placement of fixtures, finishes and furnishings. The Supreme Court has repeatedly held that all of these kinds of activities constitute “speech” within the meaning of the First Amendment. Weighed against the immense burdens Florida’s interior design law imposes on this speech is an utter dearth of evidence regarding the law’s supposed benefits to the public. Indeed, attorneys for the state stipulated during the litigation they had no evidence that the unlicensed practice of interior design — which is the norm in 47 states — poses any bona fide threat to the public, or that Florida’s licensing regime had benefited the public in any demonstrable way.

What, then, can explain the 11th Circuit’s decision to uphold the law?

The culprit is another long-term trend in American constitutional law: ever-decreasing protection for economic liberty, which receives only “rational basis” scrutiny — a standard that, in practice, means no real scrutiny at all.

Locke and cases like it thus present a quandary for lower courts. On the one hand, they know that speech receives robust protection; on the other hand, they know that economic liberties — such as the right to earn an honest living — receive no meaningful protection at all. How should lower courts reconcile those divergent lines of precedent when the government requires a license in order to speak for pay?

The short answer is: Nobody knows. The Supreme Court has never given a clear answer. As a result, lower courts, bewildered by the Supreme Court’s conflicting treatment of free specch and economic liberty, have taken a wide variety of approaches to the issue.

Unfortunately, some, like the 11th Circuit in Locke, simply throw up their hands and declare such speech to be outside the scope of the First Amendment, often without performing any serious constitutional analysis.

The problem with that approach is that it is directly foreclosed by Supreme Court precedent. Although the Court has occasionally designated certain categories of speech — like defamation and obscenity — as falling outside the scope of the First Amendment, it has also made clear that courts cannot simply declare new categories of speech unprotected unless there is historical evidence stretching back to the adoption of the First Amendment to support that conclusion. On a constitutional time-scale, however, occupational licensing is of relatively recent vintage; it did not become widespread until the 20th Century. Thus, there is no historical basis for declaring occupational speech outside the protection of the First Amendment.

Nor should it matter that interior designers are paid for their speech or that they give specialized advice. The Supreme Court has made clear that speaking for compensation is protected by the First Amendment, as is the provision of even “expert” advice. Indeed, in 2010 the Court held that a federal law restricting the provision of expert legal advice to designated terrorist groups was subject to the highest level of First Amendment scrutiny. If that speech is protected by the First Amendment, surely harmless speech about the selection of carpet and the placement of cubicles must be entitled to some level of protection.

Unfortunately, as the 11th Circuit’s ruling shows, lower courts are unlikely to provide that protection without further guidance from the Supreme Court. Although they have not been unanimous on the issue, the general trend among lower courts has been to provide little or no First Amendment protection for occupational speech.

If that trend continues, its long-term consequences will be profound. There has been an explosion of occupational licensing laws during the past 50 years, as interest groups like the Florida interior design cartel have grown increasingly adept at manipulating the levers of government power to suppress competition. In the 1950s, only 5 percent of the American work force was subject to licensing; today, that number stands at 30 percent and climbing, and it is helping destroy the engine of American prosperity.

Unless the Supreme Court acts to clarify that paid-for speech is entitled to meaningful constitutional protection, we will increasingly see those who work in “speaking occupations” such as interior design, business consulting or vocational instruction silenced by blatantly anti-competitive occupational-licensing laws.

But that doesn’t have to happen. Locke v. Shore gives the Supreme Court an opportunity to reverse this dangerous trend and instruct lower courts to provide meaningful protection to the speech of millions of Americans, while still providing states with leeway to enact genuine health and safety regulations supported by actual evidence. It’s an opportunity the Court should not pass up.

Clark Neily and Paul Sherman, attorneys at the Institute for Justice, represent the petitioners in Locke v. Shore .