Sheikh al-Sharîf Hamzah al-Fa`r, professor at Umm al-Qurâ University
The fundamental work of the lawyer is to be a proxy acting to secure the right of the one who appointed him and protect him from any oppression.
Therefore, if the lawyer abides by the truth and does not violate Islamic Law, then his work is lawful and he may even be rewarded for it if he intends to do right, even in a non-Muslim country.
On the other hand, if the lawyer intends to deny people their rights and support evil, then his work is forbidden and his revenue is illegal even if he is working in the Islamic courts of a Muslim country.
And Allah knows best.
Source: Islam Today