Unauthorized access is a violation of the Code of Ethics, but what constitutes unauthorized access depends on the listing agent's agreement with the property owner. Standard of Practice 1-16 applies to listing brokers and agents. "REALTORS® shall not access or use, or permit or enable others to access or use, listed or managed property on terms or conditions other than those authorized by the owner or seller." Unauthorized access by cooperating brokers is covered by Standard of Practice 3-9. "REALTORS® shall not provide access to listed property on terms other than those established by the owner or the listing broker."

So what is "unauthorized access?" Most listing agreements provide that the owner authorizes the use of the lockbox system under that system's rules. If the inspector is a member of the lockbox system, then the inspector is authorized to enter the property for the purposes allowed under the lockbox rules. Most lockbox rules permit entry to a listed property with an authorized lockbox for several reasons, including inspection of the property.

However, if inspectors are not permitted to access lockboxes, then the buyer's agent has violated both the lockbox rules and the Code of Ethics by permitting access by the inspector and buyer without the buyer's agent's presence. If the lockbox was a combination variety and the listing agent gave the buyer's agent the combination for the buyer's agent's needs in showing and inspections, the buyer's agent would not have authorization to give the combination to the inspector and buyer and would be in violation of the Code under Article 3 and Standard of Practice 3-9.