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.
Stockton now ranks among the top 20 fiscally healthy big cities in the nation. This comes just two years after the city came out of bankruptcy.
Incarcerated parents in Stockton can now read stories to their children through audio recordings.
Stockton Mayor Michael Tubbs is helping Stockton high school students have a better chance to find college aid.
The Stockton Arena is one of the host sites for the NCAA’s Division One Women’s Basketball sweet 16 and Elite 8 rounds in March.The event will have a huge economic impact on the city.
Michael Tubbs was sworn in as Stockton Mayor Tuesday night. His grandmother administered the oath of office.