The person who has the legal capacity to act in the name and on behalf of another is called agent in law.

The power of attorney must be carried out through what is called a power of attorney. The power of attorney is a unilateral manifestation of the person who grants it, and must comply with a series of formalities such as, for example, it must be authenticated before a notary. It is based on the person's trust in the agent, who may contract and make agreements by acting directly.

Power can cover various areas of a subject's legal capacity, so it is important to delimit it sufficiently so that it is adequate to the needs that motivate the power, but does not exceed what is necessary.

The power of attorney must specify the capabilities that are granted to the agent by the principal or principal, who may replace him or her at any time.

Within a process and for only one of the parties, there cannot be more than one representative. When a power of attorney is granted to several attorneys, the first will be understood as the main one and the others as substitutes.

It has great relevance in the field of legal entities, given that a legal entity cannot sign all agreements by itself or through its administrators and may need to use representatives to decentralize the delivery of consent.

In the bullfighting world, the figure of the representative corresponds to what has been defined up to this point, but there is a long tradition in which the authorization of a bullfighter is agreed with a single word, which has not always lent itself to integrity. The agreement normally establishes, in writing or verbally, a percentage of the agent's profit in the contracts that the companies that govern the management of the bullrings (which, in turn, are normally owned by third parties: city councils, autonomous communities, maestronzas, S.L.s...) sign with the representatives of the bullfighters, who are their agents. As these contracts are often open, that is, they depend on the capacity sold, bullfighters often do not know what they are going to charge for their performances. It is also common for bullfighting businessmen to be, at the same time, representatives of one or more bullfighters, which usually implies contracts of exchange agreements, which, in turn, has an impact on the greater difficulty of many bullfighters not attached to these "clans" to obtain posters at bullfighting fairs.