RENO, Nev. (AP) — The mystery client who hired a detective to secretly track Reno's mayor with a GPS device is trying to persuade Nevada's Supreme Court he has a First Amendment right to remain anonymous, a protected privilege he says is a cornerstone of democracy and part of “the business of politics.”

The high court allowed lawyers representing “John Doe” to file the latest brief in the case — with his true name under seal — last week so as to keep his identity secret, at least for now.

Chief Justice Lidia Stiglich set additional filing deadlines into July as the justices consider an appeal the detective filed last month seeking to overturn a Washoe County judge's order that he name the person who hired him to keep tabs on Reno Mayor Hillary Schieve and a county commissioner before the November election.

John Doe's lawyers said the U.S. Supreme Court "has repeatedly affirmed that the First Amendment protects anonymous political activity."

“For better or worse ... the use of private investigators to conduct investigations of elected officials and/or candidates is just politics as usual,” they wrote in the June 1 filing.

Schieve filed a civil suit in December seeking damages from private detective David McNeely for a violation of her privacy after a mechanic alerted her to the clandestine GPS tracking device, which was attached to her vehicle.

Sparks police determined it was purchased by McNeely. Ex-Washoe County Commissioner Vaugn Hartung joined the suit in February, alleging a GP monitor also was secretly attached to his vehicle to track his movements.

The placing of the devices on the cars wasn't illegal because no Nevada law specifically outlawed the practice at the time. But the Legislature approved and Gov. Joe Lombardo signed into law last week a prohibition on placing GPS trackers on vehicles with the exceptions of law enforcement officers with warrants and in some cases certain creditors.

Lawyers for McNeely said in last month's appeal to the state’s high court that divulging the name of a client would violate the long-accepted and expected confidentiality of a “private investigator-client relationship.”

Lawyers for John Doe joined the appeal last week, arguing that the First Amendment protects John Doe’s right to anonymously investigate elected officials to help uncover misconduct or malfeasance.

“Anonymous pamphlets leaflets, brochures and even books have played an important role in the progress of mankind. Persecuted groups and sects from time to time throughout history have been able to criticize oppressive practices and laws either anonymously or not at all,” said the brief filed by Las Vegas lawyers Alina Shell and Jeffrey Barr.

“Even the Federalist Papers, written in favor of the adoption of our Constitution, were published under fictitious names,” they said.

They said that without the assurance of confidentiality, Doe wouldn't have hired the detective to investigate any alleged misconduct by the politicians. They said earlier he'd received information that suggested the officials may have been involved in some sort of wrongdoing but haven't provided any further details.

The filing says private investigation of elected officials and candidates “has and likely will always be part of American politics.”

The late Sen. Edward Kennedy hired a private investigator while seeking re-election in 1994 to dig up damaging information about challenger Mitt Romney in Massachusetts, it said. American journalist James Callendar remained anonymous while revealing President Thomas Jefferson had fathered children with Sally Hemings, one of his slaves, it added.

In Nevada, the Culinary Union and the Las Vegas Police Protective Association hired a detective to surveil the movements of Clark County Commissioner Lynette Boggs-McDonald in 2006 to show she lived outside her commission district, the lawyers said.

They said in earlier filings in Washoe District Court that Doe had not broken any laws or disseminated any of the information gathered on his behalf and never instructed McNeely to place GPS trackers on vehicles.

The tracking device was on Schieve’s vehicle for several weeks and Hartung’s vehicle for several months, their lawsuit says.

Schieve said McNeely trespassed onto her property to install the device, which a mechanic noticed while working on her vehicle last year about two weeks before she won re-election in November.

Hartung also won re-election but later resigned to become chairman of the Nevada Transportation Commission.

Judge David Hardy said in his May 4 ruling that the use of a GPS tracking device to monitor the movements of a person could be “a tortious invasion of privacy.”