Superior Court Judge Thomas Rubinson dismissed counts filed under the law against Paul Raef, who was charged in July with being involved in a high-speed pursuit of Justin Bieber.
The 2010 law raised the penalty for those who drive dangerously in pursuit of photos for commercial gain.
The offense is punishable by six months in jail and a $2,500 fine but went unused until Raef was involved in the freeway chase of Bieber that topped 80 mph and prompted several 911 calls.
Raef still faces traditional reckless driving counts and has not yet entered a plea.
The judge cited numerous problems with the paparazzi statute, saying it was aimed at newsgathering activities protected by the First Amendment, and lawmakers should have simply increased the penalties for reckless driving rather than targeting celebrity photographers.
He also said the law could be used against photographers rushing to shoot a wedding or political rally, or even a private citizen such as himself on the way to an event that might generate photos worth selling.
While Rubinson's ruling only affects Raef's case, the law could be struck down completely if prosecutors appeal his decision, said Brad Kaiserman, an attorney for Raef.
Kaiserman argued the law was unconstitutional and meant to protect celebrities, not the public.
"This discrimination sets a dangerous precedent," he said.
Prosecutors countered that the law could be applied to people in other professions, not just the media.
"The focus is not the photo. The focus is on the driving," Assistant City Attorney Ann Rosenthal argued.
While the media is granted freedom under the First Amendment, its latitude to gather news is not unlimited, she said.
"This activity has been found to be particularly dangerous," she said of chases involving paparazzi.
Rosenthal also said the judge should look at factors specific to Raef's case, not hypothetical scenarios. She declined comment after the hearing.
The law was prompted by the experiences of Jennifer Aniston, who provided details to a lawmaker on being unable to drive away after she was surrounded by paparazzi on Pacific Coast Highway.