The juror was absent Monday when court opened for the trial of actor Lillo Brancato and testimony had to be delayed until the man was replaced with an alternate.
Court officials said the juror was arrested during the weekend after being accused of punching his 15-year-old stepson in the face.
Word of his arrest didn't reach the court until Monday.
Prosecutors allege that Brancato - who got his start in the film "A Bronx Tale" and later appeared in "The Sopranos" - was involved in the killing of an off-duty police officer while trying to get drugs.
The defense says the true culprit was Brancato's co-defendant, who was convicted on Oct. 30.