Tourists, beware.

A federal court ruling Friday may mean tour guides soon won't have to prove they're experts.

The U.S. Court of Appeals for the District of Columbia struck down licensing regulations that required Washington's ubiquitous guides to pass a 100-question exam testing their knowledge of the capital's attractions and history.

The ruling could signal broad changes for popular tourist destinations such as the Holy City.

Charleston requires tour guides to be licensed by the city's Tourism Commission in order to give tours-for-hire. First, guides must pass a challenging written and oral exam about Charleston's history, architecture, significant people and even horticulture, according to Stephen Herchak of the Charleston Tour Association.

"It's quite expansive. I'd say I spent at least a month preparing," Herchak said.

Plus, it ends up costing nearly $100 just to take the exam. It's $50 to register for the test and $48 for the study book. Then, if they pass, the tour guide license is based on their projected income.

However, Herchak said that most tour guides he knows don't mind the fees or the challenging test.

"I think people feel proud to be licensed, examined and to have proved that they're knowledgeable. It represents something about their credibility; they don't have to sell that point to somebody," he said. "Most people consider it to be something of a badge of honor."

Barbara Vaughn, public information officer for Charleston, said city officials can't comment on the matter until the legal department reviews the case.

In January, a police sting landed one rickshaw driver a $1,000 fine for acting as a tour guide without a license. City officials then told rickshaw companies that their drivers weren't allowed to take passengers on unofficial tours of Charleston for extra money.

The D.C. regulations were challenged by Tonia Edwards and Bill Main, who lead tourists on rented Segway scooters to Washington's historic sights.

In defending the licensing, the city argued that guides should be certified as having at least a minimal grasp of the capital's history and geography.

But in a 3-0 decision on a free speech issue, the Appeals Court said the city failed to present any evidence the problems it sought to thwart actually exist.

Operating as a paid tour guide in Washington without a license has been punishable by up to 90 days in jail and a $300 fine.

And the court said that even if the harms are real, there is no evidence the city's exam requirement is an appropriate antidote.

The appeals judges noted that the multiple-choice questions fall into 14 categories: architecture; dates; government; historical events; landmark buildings; locations; monuments and memorials; museums and art galleries; parks, gardens, zoos and aquariums; presidents; sculptures and statues; universities; pictures and regulations.

Earlier, a federal judge had said the requirement placed only incidental burdens on speech that were no greater than necessary to further the District of Columbia's substantial interest in promoting the tourism industry.

The appeals court reversed, saying it found the record devoid of evidence supporting the burdens the challenged regulations impose.

"The First Amendment protects everyone who talks for a living, whether you're a journalist, a professor or a tour guide," Robert McNamara, an attorney in the case, said after Friday's ruling.

The appeals court in Washington took note of a contrary decision by the U.S. Circuit Court of Appeals for the 5th Circuit, which affirmed the constitutionality of a similar tour guide licensing procedure in New Orleans. McNamara said reconsideration of that decision is being sought.

The Associated Press contributed to this report.