'Fighter' Director David O. Russell -- Transgender Groping Case Closed, No Charges Filed

"The Fighter" director David O. Russell won't face criminal charges for touching his transgender niece's breasts last month ... at least for now -- this according to the Broward County Sheriff's Office.

A rep for the Sheriff's Office tells TMZ, the investigation has been concluded and the case has been closed. According to the rep, cops will not be referring the case to the State's Attorney "because it's an allegation of simple battery that was not witnessed by law enforcement."

The rep adds, the alleged victim can still take her case to the State's Attorney on her own for their consideration -- which means it's still possible, although unlikely, that charges could be filed in the future.

As we previously reported, Russell's 19-year-old niece -- a transgender female -- told police her famous uncle felt her breasts during a workout session at a Florida hotel gym. Cops say Russell admitted he touched her chest, but insisted he had consent.

A rep for David tells us, "We are pleased that the authorities have looked into this matter and have confirmed that the investigation has been concluded and the case has been closed."

Worth noting, Russell's got an infamously ferocious temper -- back in 2004, he faced off with actress Lily Tomlin in a massive blowout on the set of "I Heart Huckabees" ... and it was all caught on tape.