Huang was covering the ambush shooting of two sheriff's deputies in Compton on Sept. 12, and a press conference outside a Lynwood hospital where the deputies were being treated.
A small group of anti-police protesters showed up outside the hospital, one shouting "I hope they die."
Huang was trying to cover the protest, but deputies pinned her to the ground and arrested her.
The sheriff's department claimed Huang didn't identify herself as a journalist - but video from the scene shows she did. The video also shows her wearing a press credential. The department also says she got too close to the confrontation between the deputies and protesters.
Huang said she identified herself as a reporter and was complying with deputies' orders, but was still arrested and detained for five hours for obstructing a peace officer.
"When she got that close that the deputies could physically grab her, she was way too close. Her place, like any good reporter, is to keep a safe distance and not become part of the story," Sheriff Alex Villanueva said.
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The DA's office says there is insufficient evidence to show that Huang broke the law. The county Inspector General is also investigating the case.
"I am gratified that the District Attorney's Office has reviewed the evidence, including my video recordings of law enforcement activity, and reached the conclusion that it did," Huang said in a written statement. "I plan to ask for a finding of 'factual innocence' that will wipe this unlawful arrest from my record."
"More than ever, I am grateful for the First Amendment, which entitles all Americans -- not just journalists -- to the rights of free speech and assembly."
"We are pleased that the DA's office has declined to pursue a case against Josie Huang," said Herb Scannell, president and CEO of Southern California Public Radio, which operates the station.
"Unfortunately, journalists are increasingly under attack. They play a critical role in our democracy and their safety must be protected at all times."
The LASD issued a statement Thursday:
"The Los Angeles County Sheriff's Department values the media and highly respects the freedom of the press. We are advocates of responsible reporting and strongly believe in transparency.
With regard to the obstruction arrest (148pc) of Ms. Josie Huang, it is unfortunate this incident took place during a time in which our focus was on the horrific attempted assassination of two of our deputies. The events during that time were very tense and rapidly evolving.
At that same time, our personnel were dealing with protesters who were blocking the driveway to the hospital emergency room and chanting for our wounded deputies to die, which could also be heard by their family members.
Unfortunately, Ms. Huang inserted herself too close to the highly charged situation as an arrest was being made.
This case was investigated and all the elements of the crime were present. The case was presented to the Los Angeles County District Attorney's Office and they ultimately declined to prosecute. This is not uncommon, as they must weigh many factors into their decision.
An internal investigation was opened in this matter and appropriate administrative action will be taken. We are unable to provide further comment at this time, due to personnel privacy laws."