It added that a unilateral declaration of divorce before a religious court does not fall under the scope of the regulation, and said the case must be resolved under German law.
The ECJ does not decide the dispute itself, and the court in Munich will take a final decision on the issue.
What's instant divorce?
Triple talaq divorce has no mention in Islamic law or the Koran, even though the practice has existed for decades.
Islamic scholars say the Koran clearly spells out how to issue a divorce - it has to be spread over three months, allowing a couple time for reflection and reconciliation.
Why must "talaq" be said three times? Under some interpretations of Islamic law, a man can divorce his wife and get back together with her - but only twice. After the third divorce, the marriage is completely over and cannot be started again without an intervening marriage to someone else.
Most Islamic countries have now banned triple talaq.