Final answer:
In Washington, a buyer's agency is created through a contractual agreement according to state law, while common law in other states allows for the formation of a buyer's agency through mutual consent and the agent's authority to act.
Step-by-step explanation:
In Washington, a buyer's agency is created through a contractual agreement between a real estate agent and a buyer. The agreement outlines the duties and responsibilities of the agent towards the buyer, including the agent's fiduciary duty to act in the best interests of the buyer. This agency relationship is formed according to Washington law.
On the other hand, common law governs the creation of buyer's agencies in many other states. Under common law, an agency relationship is typically formed when the agent has the authority to act on behalf of the buyer, and the agent and buyer have mutually consented to the arrangement. There may not be a written agreement required, but the agent still owes a fiduciary duty to the buyer.