All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
If the divorce was issued by the non-Muslim judge, then it does come into effect, as disbelievers have no guardianship over Muslims. Allaah The Almighty Says (what means): {never will Allaah give the disbelievers over the believers a way} [Quran 4:141]
Hence, the woman is still married to this man.
However, if the husband was summoned by the order of the judge and was commanded to divorce his wife without coercion and he did, then the divorce has come into effect.
Allaah Knows best.