Is agency permissible in pursuing, proving, and litigating claims?

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Agency is permissible in pursuing rights, establishing them, and in litigation concerning them, regardless of whether the principal is present or absent, healthy or ill. This is the opinion held by Malik, Ibn Abi Layla, Abu Yusuf, Muhammad, and Al-Shafi'i. The primary evidence for this is that it is an established right where representation is permissible, thus the owner may delegate representation without the opponent's consent, just as in cases of absence or illness, or payment of a debt. Furthermore, there is the consensus of the Companions (Sahaba), may Allah be pleased with them. For instance, Ali (may Allah be pleased with him) delegated Aqil before Abu Bakr (may Allah be pleased with him), stating that any judgment in his favor should be for him, and any judgment against him should be against him. Abdullah ibn Ja'far was also appointed as an agent by Uthman, who stated, "Litigation has pitfalls, and Satan attends it, and I dislike attending it." These incidents spread widely, and since they were in a position to become widely known, the lack of reported objection serves as evidence. Necessity also calls for this, as a person might have a right or be accused, but lack skill in litigation or simply prefer not to handle it personally.