It was only a "training exercise"... honest judge (emphasis mine):

With a horrified suspect watching, Huntington Beach police planted evidence - a loaded revolver - in the man's car during a DUI accident investigation in January, the Weekly has learned.
...
Brian Knorr, the uniformed officer who threw the weapon, lowered the trunk lid with the gun inside and stepped back, allegedly waiting for an unsuspecting fellow officer to find it during a search, according to testimony. The officer assigned to search the vehicle eventually located the gun and, startled, turned to Cox holding the revolver in both hands. This officer stared at Cox, who began to panic at the scenario of a weapons charge. Knorr walked over, "elbowed that cop and took the gun back," said Cox.

Laughter erupted.
...
By the time of the late October trial against Cox, however, four officers testified that the gun toss was no reason for public alarm. They admitted that none of them had mentioned the gun in official reports before Cox's complaint. And, though the officers professed amnesia on certain details, they all shared with jurors an identical excuse: the planted gun was merely a prop in a routine "training exercise" for a junior cop at the crime scene.

If you read the rest, you'll find the details on how the judge refused to allow certain evidence into court in order to protect the "privacy" of the officers.  I'll allow you a moment to pick your jaw up off the floor.  The suspect was found guilty on multiple different charges by the way.

I'm sure the residents of Orange County feel so much safer knowing they have such a highly professional police force watching over them.  Of course, the residents of Orange County barely even knew about this thanks to the efforts of not just the police, but also the judge in the case who helped cover it all up.  Via The Agitator.