Immigration officials sought to deport Luis Gonzalez-Marquez to Mexico after his prison sentence for robbery, saying his father’s U.S. citizenship does not make him a U.S. citizen because they were not biologically related. But a federal appeals court disagrees and says the Napa man is a citizen entitled to remain in the United States.

Federal law, which allows a naturalized U.S. citizen to confer citizenship on a minor child after immigration, “does not expressly require a blood relationship to the citizen parent,” the Ninth U.S. Circuit Court of Appeals in San Francisco said in a 3-0 ruling Friday.

Gonzalez-Marquez was born in 1987 in the Mexican state of Chihuahua, with no father listed on his birth certificate. Four years later, his mother’s husband, Jesus Gonzalez-Hernandez, went to the municipal registry with his wife and declared the child to be his legitimate son. Under the state’s law, the child’s birth certificate was changed to include his father, with no need for the formal adoption that most governments require.

The family entered the United States as legal residents in 1994, and the father became a U.S. citizen two years later, said the son’s lawyer, Richard Coshnear. After he turned 18, Coshnear said, the son pleaded guilty to robbery and served time in prison.

Immigration officials then moved to deport him and have kept him behind bars for most of the past three years, the lawyer said. A noncitizen can be stripped of legal residency and deported for committing a crime classified as an “aggravated felony.”

Immigration courts upheld the deportation, but the appeals court overruled them Friday and said Gonzalez-Marquez, now 26, is a U.S. citizen, not just a legal resident, and thus cannot be deported.

U.S. law “honors concepts of family law from foreign countries,” including the Mexican state that recognized Jesus Gonzalez-Hernandez as the child’s father, the court said. The man “undertook the legal obligation to raise (the child) as if he were his biological or adopted son,” and the United States must respect that relationship, the court said.

Coshnear praised the ruling. He said his client made “one mistake” as a youth, but now has “an opportunity to rehabilitate himself and lead a law-abiding life here.”

Bob Egelko is a San Francisco Chronicle staff writer. E-mail: begelko@sfchronicle.com