The plaintiffs say the "shelter has a duty to help, not harm, homeless dogs and cats."
The Animal Legal Defense Fund along with three people from Stockton filed the lawsuit against the City of Stockton.
The suit is not asking for money, only that the animal shelter follow the law.
The shelter is required to hold strays for at least 6 days before euthanization.
But Animal Legal Defense Fund Attorney Jenni James says the shelter's records show a different story over a one year period.
"Early euthansias are happening, 1,500 animals were euthanized before the expiration of the Stockton shelter's minimum holding period," says James.
James says 80 percent of the animals are behind locked doors where the public never sees them.
"Only about 20 percent of the animals are truly being given a meaningful chance of adoption," says James.
The City of Stockton is not commenting on the lawsuit.
A judge has reduced Stockton Mayor Anthony Silva's felony eavesdropping charge to a misdemeanor. The case stems from a 2015 strip poker party at a youth camp Silva runs.
Friday is National Coffee with a Cop Day and more than 2,000 law enforcement agencies are taking part in the event.
Stockton Police officers on the streets are upgrading their body cameras to record incidents, in some cases, before they happen.
Motorists driving through Stockton will see a change on Interstate 5 on Wednesday as one of the four northbound lanes from Country Club Boulevard to Hammer Lane will be the first carpool lane along that stretch of the highway.
Stockton Mayor Anthony Silva returned to court Wednesday in Amador County on charges of providing alcohol to minors and recording a game of strip poker with teens at a summer camp last year.