Forging someone else's signature is an illegal act. Without the entrustment or authorization of the client, it is illegal to sign for others without authorization, which will lead to serious criminal responsibility. Authorized by the licensor, it is legal to sign instead of the licensor. This phenomenon is very common in real life. Some are trivial matters of life, others are important economic activities and important matters, and the client authorizes others to sign them.

Legal basis: Article 171 of the Civil Law: If the actor has no power of attorney, exceeds his power of attorney or continues to act as an agent after the termination of his power of attorney, it will have no effect on the principal without ratification by the principal. The counterpart may urge the principal to ratify it within 30 days from the date of receiving the notice. If the trustor fails to declare it, it shall be deemed as refusal to ratify it. Before the act committed by the actor is ratified, the bona fide counterpart has the right to revoke it. Revocation shall be made by notice. If the act committed by the actor is not ratified, the bona fide counterpart has the right to demand the actor to perform the debt or demand the actor to compensate for the damage he has suffered. However, the scope of compensation shall not exceed the benefits that the counterpart can obtain when the principal ratifies. If the counterpart knows or should know that the actor has no right to act as an agent, the counterpart and the actor shall bear the responsibility according to their respective faults.