is working for a commission allowed. for example, a notary/lawyer may charge 2% as fees on the value of all transactions he handles, e.g, he will charge 2% on the sale of lands, whether one piece of land is worth USD1M or USD200M, notwithstanding that his profession work is almost the same in both cases.
Another example, is that is a Muslim lawyer allowed to charge contingency fees. say a client is claiming USD1,000 from its debtor. can the Muslim lawyer charge 10% (according to local customs) on the amount he eventually recovers from the debtor or does he have to charge a fixed fee?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

According to the agreement of the scholars if the commission is a known amount and not a percentage of the cost of the transaction, then it is permissible to take it, because this is considered as permissible hiring or permissible brokerage. However, if this commission is a percentage of the profit, then this is a controversial issue among the scholars . The majority of them are of the view that it is a condition for the commission to be known, but since it is a percentage from the profit, then this makes it unknown. However, some scholars are of the view that it is permissible for the brokerage fees to be a percentage from the profit. This last opinion is a considerable opinion and it is permissible to act according to it.

Furthermore, it is acceptable to agree with the lawyer for him to take a known amount when he would have completed the work and would have won the case [in the court] as this is considered as a conditional payment (Ji’aalah), and the lawyer does not deserve anything unless he would have completed the work and would have won the case.

It should be mentioned that in principle the profession of a lawyer is permissible because it is an authorization to conduct lawsuits for clients and defend them. The following conditions should be met for the profession of a lawyer to be permissible:

1-    Observing the truth and avoiding telling lies: this means that he should study the case and if he sees that his client is right, he would defend him, and if he sees that his client is wrong, he would clarify this to him and would advise him to abandon the lawsuit.

2-    The case should be taken to an Islamic court if any, and if the lawyer’s client chooses a court that is run by man-made laws, then it is not permissible for him to defend his client. However, if there is no Islamic court and the client does not have a means to get back his right except by taking his case to a court run by man-made laws, or that the case against the client is taken to such a court, then it becomes permissible to take the case to such a court.

For more benefit, please refer to Fatwa 89659.

Allaah Knows best.