Praise be to Allaah.
The position of a lawyer in the Islamic judicial system is that he is the deputy or agent of the one of the two parties who has appointed him to represent him, either the plaintiff or the defendant. The one who appointed him should be moderate in seeking his rights and be fair with his opponent. If both parties adhere to that it will be better for both of them, and that will help the judge to make a decision in cases of dispute. If the disputant or his deputy insist on deceiving and going to extremes in their arguments in order to make gains even if they are haraam, then they are sinning and consuming people's wealth unlawfully, and they are causing confusion to the judge, unless Allaah guides the judge by His grace and mercy and help them to make the right decision, so that the dispute may be resolved fairly.
And Allaah is the Source of strength. May Allaah send blessings and peace upon our Prophet Muhammad and his family and companions.
From Fataawa al-Lajnah al-Daa'imah, 32/501.