Britain's Prince William and his wife Catherine, Duchess of Cambridge, pose for pictures at Yellowknife airport July 6, 2011.[Photo/Agencies]

LOS ANGELES - More than a dozen years after Princess Diana's death on a Paris highway sparked an international backlash against the photographers who chased her, her son's visit to the paparazzi hotbed of Southern California has officials on high alert.

Prince William and bride Kate will arrive Friday in a state that in the years since Diana's death has passed three laws intended to curb paparazzi abuses. The most recent change, inspired in part by Jennifer Aniston's experiences, raises the penalties for aggressive driving by paparazzi from mere infractions to misdemeanors punishable by up to six months in jail and a $2,500 fine.

The newlyweds are two of the world's hottest celebrities right now and law enforcement officials who have hoped for a situation to test the new laws think they may get one when the perfect storm of British and Los Angeles celebrity photographers jockey for shots of the royal couple.

"We want to make sure everybody has a safe trip," Los Angeles police Sgt. Mitzi Fierro said. She said that would extend to residents and the public, not just the heavily guarded royal couple.

Beginning Friday morning, police plan to close the street of the British consul-general's home in Hancock Park, where the couple will stay on their weekend visit. Officers have already obtained "No Trespass" letters from neighbors, which will be used to arrest anyone who enters the adjoining properties to try to get pictures or glimpses of the couple.

"If anybody is behaving inappropriately," Fierro said, "we're going to take whatever legal police action we can to enforce the laws."

That includes a trio of anti-paparazzi state laws that are ostensibly unused and have done little to thin the ranks of those who track celebrities' every move.

Photo agencies expect shots of the newlyweds in LA to sell for anywhere from $25 to $1,000. "Every move they make, everything she does, there will be 10,000 images," Bauer-Griffin photo agency co-owner Frank Griffin said of the upcoming trip.

"This will be a pretty good test of where we're at," said Mark Geragos, a celebrity attorney who has helped clients deal with aggressive shooters over the years.

For the LA equivalent of royalty — movie, television and increasingly, reality TV stars — daily paparazzi interactions fuel their stardom. Yet clashes sometimes occur between photographers and celebrities, such as Russell Brand and Mike Tyson, who were arrested after airport scuffles.

Many are surprised that seven months after the law against aggressive driving went into effect, no one has been charged.

Matt Schonbrun, a deputy Los Angeles city attorney, said he expected to see plenty of cases after the law was passed in January. But reports from celebrities of misconduct haven't come in, and a 911 call documenting a dangerous pursuit is necessary, he said.

Private security firms hired by celebrities even offered to put video cameras in their cars to capture what happens when they are pursued by paparazzi.

"These incidents are happening every day. It's really scary and coming to a critical mass," Schonbrun said. "We need a test case and we want the first ones to be egregious. Once that call is made we can get the ball rolling."

Schonbrun said the main challenge for law enforcement is to prove there was intent to make an image for commercial gain. "We need to establish that the picture is going to be sold and it's an undertaking on our part to follow the money trail," he said.

Kain Guercci, director of operations at Talon Executive Services, an Orange County company that provides security for corporate executives and celebrities, said the lure of a big paycheck makes some paparazzi fearless.

"If I'm getting a picture that will pay between $1,000 and $5,000 and I'm going to get a misdemeanor on my record, it just doesn't compute," Guercci said.

The sponsor of the driving bill, Congresswoman Karen Bass, D-Calif., pushed for the stiffer penalties while in the state assembly, in part because of hearing stories from Jennifer Aniston about being hounded. In one instance, the actress told Bass she had been surrounded by photographers on Pacific Coast Highway and unable to drive away.

Two other laws — which allow celebrities to receive hefty civil judgments if a photograph is taken where they have an expectation of privacy — have been on the books for longer and have gone similarly unused.

Aniston did use one of the laws, which was enacted after an incident involving Arnold Schwarzenegger, to sue a man who photographed her topless at her home without permission in 2005. The case settled before trial, but it appears to be the only time a celebrity has used the civil invasion of privacy provision against a photographer.

Although many stars are passionate about cracking down on aggressive shutterbugs, they are less inclined to be called as a possible witness if a case is brought to trial, Schonbrun said.

In public places, some LA-area police agencies are employing more mundane rules against the paparazzi.

Los Angeles police Cmdr. Kevin McCarthy recalled an instance where he sent officers to the school one of Britney Spears' children was attending. Every time she came to pick the boy up, pandemonium broke out and numerous residents called police.

"These guys were parked on side streets, they just came out of nowhere, double parking in the street, getting as many shots as they could," McCarthy said.

Lt. Tony Lee of the Beverly Hills Police Department said his department in recent years has frequently given traffic citations to aggressive photographers. However, the department hasn't seen a case yet that rises to a level where the new law could be applied.

The LAPD also ran a couple of traffic operations, where motorcycle officers would saturate the route being driven by a celebrity, then pull people over for traffic violations. But such operations did little to deter paparazzi looking for the big-money shot, said McCarthy.

Giles Harrison, a celebrity photographer and owner of London Entertainment Group, said he's witnessed the extra enforcement efforts, including on the beaches of Malibu, where paparazzi are being cited for shooting without a commercial license.

Harrison jokes that he's the "world's most infamous pap" — a reference to a 1998 incident involving Schwarzenegger that partially prompted California's initial effort to reign in the paparazzi. He and another photographer were convicted of misdemeanor false imprisonment and sentenced to jail for boxing in Schwarzenegger and his family as they sat in their Hummer.

Citing the incident and the death of Princess Diana, the California Legislature passed its first anti-paparazzi measure a year later. It created hefty civil penalties available to stars whose privacy was invaded and was used by Aniston in her lawsuit.

Years later during his tenure as governor, Schwarzenegger signed an update that makes outlets that publish illegally-obtained images liable for damages, but that version has never been used.

Their legality remains in question and many First Amendment attorneys doubt they would withstand judicial scrutiny if applied.

Harrison said anti-paparazzi laws are unnecessary, that there are plenty of regulations on the books to protect both stars and private citizens. He blamed many of the incidents of bad behavior on untrained shooters who crossed the line.

And for now, it seems, stars are relying on those already established laws, and the occasional assist from police, to keep from being photographed.

Lee, the Beverly Hills police lieutenant, said some stars who aren't familiar with his city have actually come to the police station asking to be escorted out of town.

"It doesn't happen often," Lee explained, "but if we feel there is a safety risk for them, then we will do what we can to ensure their safety."