In agency by estoppel, representation must precede reliance

An agency may be expressed or implied from the act of the principal, from his silence or lack of action, or his failure to repudiate the agency knowing that another person is acting on his behalf without authority. Acceptance by the agent may be expressed, or implied from his acts which carry out the agency, or from his silence or inaction according to the circumstances.

Agency may be oral unless the law requires a specific form. However, to create or convey real rights over immovable property, a special power of attorney is necessary. Thus, when a sale of a piece of land or any portion thereof is through an agent, the authority of the latter shall be in writing, otherwise, the sale shall be void.

For an agency by estoppel to exist, the following must be established: (1) the principal manifested a representation of the agents authority or knowingly allowed the agent to assume such authority; (2) the third person, in good faith, relied upon such representation; (3) relying upon such representation, such third person has changed his position to his detriment. An agency by estoppel, which is similar to the doctrine of apparent authority, requires proof of reliance upon the representations, and that, in turn, needs proof that the representations predated the action taken in reliance. (G.R. No. 144805)