In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
A woman can serve as a judge even as a man does as long as she is qualified.
In responding to your question, Sheikh Ahmad Kutty, a senior lecturer and an Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states:
A woman can serve as a judge even as a man does as long as she is qualified. It is one’s ability to serve the position that matters and not gender differences. Not all men are qualified to serve as judges; likewise, not all women are eligible to serve as judges.
We said the view of several scholars of the past (such as Abu Hanifah and Ibn Jarir At-Tabari) and many modern scholars. For sure, others oppose it. Since there is no revealed text to support the latter view, it is based on their subjective interpretations.
Almighty Allah knows best.