PHOENIX — The owner of a business in an industrial area of Phoenix says he was running a legitimate porn studio where amateurs could rent cameras, lights and props to create their own sex scenes with the help of a model.

Authorities, however, say it was nothing more than a cleverly disguised brothel raking in $40,000 a month in profits.

Owner William James Hartwell denies running a prostitution ring and in court documents accuses the government of criminalizing free speech protected by the First Amendment.

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He will go on trial next week on charges of operating a house of prostitution, sex trafficking and sexual assault in a legal clash over the First Amendment.

Hartwell, 56, says the sex acts that were recorded and photographed amount to constitutionally protected free speech practiced in the same way as professional porn studios that legally operate.

“All sexual conduct that took place at the studio was for the purpose of exploring and expressing an individual’s sexuality via safe and legal adult content creation,” Hartwell wrote in court records.

A call left for Rick Poster, an attorney for Hartwell, wasn’t returned.

Police say female employees who took customers into rooms would insist on shooting a minutes-long video or taking 10 photos with sexual content before the cameras were discarded and they began to have sex.

Prosecutors say those images were taken in a bid to guard against any future prostitution allegations.

To get into the location, men had to respond to an online ad and were given the address only after they called from a nearby gas station. Once inside, documents say, they had to show their genitals as a way to guard against undercover officers.

The investigation was launched in 2012 after police received a tip about the business.

Authorities sent informants who posed as customers or prospective employees. One informant said Hartwell told her during a job interview that the studio provides customers with porn production space, cameras, condoms and a “free porn girl,” court documents state.

A website for the business said customers couldn’t give their money to anyone other than a receptionist - and could only do so for equipment rental and studio fees. Authorities say the sex workers were told they didn’t have to worry about the legal ramifications of prostitution because they didn’t handle any money.

Investigators say customers were allowed to pick up a USB drive with still photos or videos a few days after a sexual encounter. About half the customers actually returned to pick up the images.

Several women who worked at the studio have pleaded guilty to related charges and are expected to testify at the trial.

“Prosecuting the defendant and workers for crimes related to prostitution is lawful,” prosecutor Monica Sochacki said in court records.

Hartwell is also charged with sexually assaulting two women at the business who said they didn’t want to participate anymore.

It’s unclear whether any of the customers were charged with crimes.

The Maricopa County Attorney’s Office, which is prosecuting Hartwell, declined to comment on the case beyond what is in the court records.