Limits of Buyer Responsibilty to Buyer's Agent

[Katie Rogers]

A couple months ago, I made an offer for a house via my buyer's agent.  This was the first deal this agent and I worked on together.  Throughout the process, I have been disappointed with this buyer's agent's lack of timely response.  The seller accepted another buyer's offer.  As of today, the house has fallen out of escrow and is back on the market.  If I restart the offer process with a different buyer's agent and I win the house, can the first buyer's agent demand a commission even though she did not successfully negotiate for the house the first time?  Or do I have to work with her on this house until my offer is accepted, or the house closes for another buyer?  California law prevails.