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.
Traditionally, families have spent Thanksgiving morning at home getting turkey and trimmings ready for the big meal. Thousands of people in Stockton are developing a new tradition.
More than 2,000 families are expected to wait in line in Stockton Monday morning, hoping for free Thanksgiving baskets to take home.
The City of Stockton announced today the hiring of a new fire chief. The new chief brings 25 years of experience to the job.
Friday's terrorist attacks in Paris have shocked the world, particularly people who have visited the French capital. Capital Public Radio's Rich Ibarra spoke to a Stockton couple who were recently there.
Boaters and businesses in the Delta are plagued again this year by water hyacinth clogging rivers and marinas.