In the first place, we’d like to make it clear that as a lawyer or a consultant, one should be committed to the principles and ethics of Islam. One is not allowed to violate any guidance of the religion. One cannot help a person who is a thief in order to acquit him when you know he is guilty. There is no evidence in Shari`ah that generalizes saying the career of a lawyer is haram, but, the conclusion from studying the Qur’an and Sunnah draws limits for this job.
Focusing more on the issue, following is the fatwa issued by the prominent Muslim scholar Sheikh `Atiyyah Saqr, former Head of Al-Azhar Fatwa Committee: “Al-Bukhari and Muslim both reported that the Prophet (peace and blessings be upon him) said, “I am only a human being, and you people have disputes. Maybe someone amongst you can present his case in a more eloquent and convincing manner than the other, and I give my judgment in his favor according to what I hear. Beware! If ever I give (by error) somebody something of his brother’s right, then he should not take it, as I have only given him a piece of Fire.” In another Hadith, the Prophet (peace and blessings be upon him) said, “Whoever helps another in a dispute wrongfully, he incurs the wrath of Allah till he stops doing so.”
These Hadiths, along with many others, explain that it is really dangerous to help others in disobedience and getting what does not belong to them. A lawyer is working on behalf of a person and thus should always cherish the dictates of taqwa (piety and fear of Allah). If he knows for sure that his client is innocent or has the right, then there is nothing wrong in acting on his behalf. He will get reward from Allah in addition to his fees, since this will be cooperation in good deeds and defending the oppressed.
However, if the lawyer knows that his client is guilty or does not have the right in the claim, then he is severely warned against helping him and the fees he takes are surely unlawful, as stated in the previous Hadith.
In At-Tabarani, there is a Hadith that reads: “Whoever walks with an oppressor to help him in his oppression while he knows that he is as such, he places himself out of the fold of Islam.” This hadith shows that if a person believes that helping an oppressor is halal (lawful), he is totally out of Islam.
In his brilliant book Al-Ihya’, Imam Al-Ghazali wrote:
A person working on behalf of another is authorized to take fees, permissibly, if he is defending him in what is his right. However, if he is helping him in what is not his right or defending a person who is really guilty, the fees are totally unlawful. All of us should always remember the words of Allah: “Lo! ye are they who pleaded for them in the life of the world. But who will plead with Allah for them on the Day of Resurrection, or who will then be their defender?” (An-Nisaa’: 109)”