There can be three types of powers given to a person to act on behalf of others – express, apparent, and implied. Express means the power comparable to the owner, granted mostly through formal written documents which create a legal binding to perform the duty of another person.
Such rights can be granted by words or conduct that can be reasonably interpreted and it leads the agent (clients) to believe the principal desires her to act in the manner, where the court looks for the objective manifestation of the principal.
The extent of the agent’s control may depend on the understanding of the words used during the appointment. If the selection is made in writing, the document will be examined, and if it is oral the scope is taken, as a matter of evidence.
If the agent acts outside the capacity, they may be liable as per regulations and the 3rd party, for the breach of the warrant.