Editor’s Note: This story was originally published in October 2015 and has been updated.

Story highlights

Nevada is the only state that legalizes prostitution in the form of brothels

But state law prohibits prostitution in Clark County's Las Vegas

Brothels can't advertise in any city or county that doesn't allow them

CNN  — 

Sex workers do business in every state, but only in Nevada is prostitution legalized, specifically in brothels.

Nevada’s bordellos gained attention after former NBA and reality TV star Lamar Odom collapsed inside one, the Love Ranch in Crystal, about 60 miles outside Las Vegas, in October 2015.

Here are a few things to know about Nevada’s sex-trade establishments.

Brothels not legal in big cities

Nevada law allows counties with a population below 700,000 to offer brothel prostitution.

That means no legal prostitution in Clark County, where Las Vegas is. County law prohibits brothels in Washoe County, home to Reno, and several other counties.

Nevada provides a tolerant atmosphere toward prostitution, and though illegal today in Las Vegas, the city remains renowned for its ongoing sex trade – as well as its slogan of “What happens in Vegas, stays in Vegas.”

Nineteen brothels operate in Nevada, down from 36 in the peak years of the mid-1980s, according to the Las Vegas Review-Journal. The brothels are open for business in eight counties, though four more counties allow brothels but don’t have any, the newspaper said.

There are three kinds: the small frontier brothel along remote stretches of highway, the small brothel in an isolated small town, and the large, urban-like bordellos outside Las Vegas, Reno, Lake Tahoe and Carson City, according to a University of Nevada, Las Vegas, study.

Testing aims to prevent STIs

The state board of health requires sex workers to undergo testing for sexually transmitted infections.

Brothels cannot employ prostitutes until test results “do not show the presence of infectious syphilis, gonorrhea, chlamydia trachomatis or infection with the human immunodeficiency virus (HIV),” the state regulations say.

Monthly blood testing is required for HIV and syphilis.

Sex workers must also require patrons to use condoms.

Brothel business applicants must disclose financing and management and undergo a background investigation.

‘Herbal Viagra’ is not Viagra

How the deal for sex is made

UNLV sociologists Barb Brents and Kate Hausbeck described how the brothels operate in a 2006 paper.

In general, initial contact takes place in a central parlor. Customers approach women from a lineup or at the brothel’s bar.

The price for sex is negotiated “behind closed doors in the individual prostitute’s room,” the sociologists said.

Female sex workers reported they can refuse clients, and one common way is setting too high a price.

“The more elite prostitutes had the most control over who they service. Some reported that they only dealt with regulars,” the UNLV report said.

Brothel stars in HBO reality show

One brothel had its own HBO series, and it featured Dennis Hof, also the owner of the brothel where Odom fell ill and became unconscious.

Nevada’s Moonlite Bunny Ranch outside Reno has been the subject of the series “Cathouse.” HBO said the series began after the brothel was featured in two specials in 2002 and 2003 that became the network’s “highest-rated adult documentaries.”

The episodes utilize “hidden cameras in the brothel’s ‘party rooms’ to eavesdrop on customers and ‘working girls’ before, during and after sex,” HBO’s website said.

Brothels’ advertising is limited

Nevada brothels can’t advertise in any city or county that doesn’t allow prostitution.

The American Civil Liberties Union challenged that law while representing brothel owner Bobbi Davis of Nye County’s Shady Lady, West Wendover High Desert Advocate, and Las Vegas City Life.

Arguing the law violated the First Amendment, the ACLU won in a federal trial court, but lost in federal appeals court.

The U.S. Supreme Court later refused to hear the case in 2011, allowing the law to stand.

The law has been on the books since 1913, UNLV law student Denise S. Balboni wrote in 2007.

Nevada lawmakers didn’t leave a legislative history, making it difficult “to speculate about what motivated legislators nearly a century ago,” Balboni wrote.

“It is reasonable to presume that their intent related in some way to preserving the health, safety, welfare and morals of the state’s citizens,” she wrote.

Meanwhile, as every Las Vegas tourist knows, escort services and their promoters pass out advertisements to passersby on the Strip today.