A three-judge appeals panel, in a decision issued in San Francisco on Monday, rejected claims by alleged gang member Yancie Young that the injunction was unconstitutional.
"We conclude sufficient, credible evidence supports the trial court's conclusion that the North Side Oakland (gang) is a criminal street gang whose activities have created a public nuisance in the designated area," the court said.
The injunction was issued by Judge Robert Freedman in June 2010 after hearings on a request by City Attorney John Russo for the order.
The injunction bars the 15 named individuals from associating with other known gang members except when going to church, work, school or appointments within an area known as the Safety Zone.
It also prohibits them from intimidating witnesses, possessing firearms, possessing or selling drugs and creating graffiti.
In his appeal, Young challenged both the constitutionality of the injunction in general and the decision to include him in the order.
The appeals court ruled against him on both arguments.
It said there was substantial evidence to justify including him in the injunction, including previous misdemeanor convictions for gun possession, domestic battery and marijuana possession, as well as discovery of gang-related paraphernalia in a probation search of his home.
Young's defense attorney, Michael Haddad, was not immediately available for comment on whether he will appeal to the California Supreme Court.
The city attorney's lawsuit seeking an injunction was filed under the legal theory that the gang activities constituted an illegal public nuisance.