Another judge had dismissed the aggravated mayhem count against Enrique Gonzalez, the boy's father, and Travis Gorman, although a charge of willful cruelty to a child remained. But prosecutors refiled the mayhem charges and Judge Gary Orozco approved them Friday, the Fresno Bee reported.
Investigators say Gonzalez held his son down while Gorman inked the gang tattoo. The men are members of the Bulldogs.
Defense lawyers say the aggravated mayhem charge has been used in California for assailants who mutilate their victims.
The Bee suggested Orozco's ruling could mean parents facing serious felony charges -- the maximum penalty is life -- for having boys circumcised or getting children's ears pierced.
"This is precedent-setting and I don't like it," said Gonzalez's lawyer, Douglas Foster.
Foster said Gonzalez made a "horrible decision" but did something that is not equivalent to cutting off an arm or putting cigarettes out on a victim's body.
Gonzalez and Gorman are scheduled to be tried next month.