Whether you can sue a buyer who backs out at the last minute will depend on the terms in your purchase agreement. In most cases, a purchase agreement will contain contingencies that were written specifically to protect the potential buyer from being sued in these types of circumstances. However, the seller will likely be able to keep the earnest money that was put down when the purchase agreement was signed. Consult with the Gilbert real estate lawyers at Denton Peterson Dunn for advice on your specific situation.