"That 70s Show" star Lisa Robin Kelly won't face any additional jail time in her domestic violence case -- because the L.A. County D.A. has declined to file charges.
Law enforcement sources tell TMZ, the alleged victim -- Lisa's male roommate -- refused to cooperate with authorities, which made the case impossible to prosecute.
TMZ broke the story ... Lisa was arrested in March on a felony charge of corporal injury on a spouse after allegedly roughing the guy up in their apartment.
Lisa has claimed she was innocent from the beginning -- and insists she wasn't drunk or high at the time of her arrest, despite the jarring mug shot.