The laws of agency vary by state. This is a general overview.  Be sure to check with your agent on the laws for your state.  


Real Estate Brokerage began with a seller listing their home with a real estate broker. Anyone who wished to see that home had to contact the listing broker. If the house next door was listed with another broker a potential buyer had to contact that listing broker in order to see or buy that property. A broker could only show his listings.
To better serve the buyer-customer, brokers conceived the idea of a multiple listing service (MLS) where each member broker would share information about their listings and invited other brokers to sell them. This way they they would be able to sell any house listed in the MLS and share in the commission. By virtue of the MLS, both the buying and selling brokers became agents of the seller. Agency remained intact.
The ability to have other brokers show and sell property worked so well that brokers decided to hire real estate agents to work for them and share in the commission. Because the real estate agent worked directly for the listing broker, they too became agents of the seller.


Sub-agency is where one real estate company represents the seller and another real estate company represents a buyer without a buyer's agency agreement. The agent working with the buyer who represents the seller; thus the term "sub-agency." 


Prior to the formation of Buyer Agency, every person involved in the real estate process was an agent of the seller and all fiduciary duties were owed strictly to the seller. Buyers, feeling that the deck was stacked against them, started demanding that they have equal representation in the transaction; therefore, Buyer Agency was formed.  Certain fiduciary duties are owed to the buyer under Buyer Agency.
The real estate agent must disclose the form of agency that he/she is working under when scheduling appointments to show property. In some states, if a buyer cannot decide about agency representation, the appointment is scheduled as a non-agent or other agent. (see below)
NOTE: No matter what agency relationship is formed all parties have a right to full disclosure of all material facts, plus fair and honest treatment.


Dual Agency is not allowed in all states. Dual Agency means that one office represents two principals in the same real estate transaction. One agent has the listing agreement with the seller. This agent or another agent with the same real estate firm has a buyer under a buyer agency agreement, thus dual agency is formed. The intention of the various laws is to insure fairness to both parties. Discuss this with your Realtor to insure that you understand the laws in the state where you are conducting a real estate transaction.


A non-agency or other agency is created when a real estate agent is working with a buyer that has not made a decision on agency. This buyer is not entitled to any information about the sellers and should not give any information to the real estate agent that the buyer would not want the seller to know.