Final answer:
Yes, the attorney could be subject to discipline for their action due to their duty of loyalty and confidentiality to the client.
Step-by-step explanation:
Yes, the attorney could be subject to discipline for their action. Attorneys have a duty to maintain the confidentiality and protect the interests of their clients. By promptly producing the information and document required by the subpoena without consulting the client, the attorney may have violated their duty of loyalty and confidentiality.
Attorneys are generally required to consult with their clients before taking any substantive action related to the client's legal matters. In this case, the attorney should have informed the client about the subpoena and sought their instructions before producing the requested information and document.
If the attorney's conduct is found to be in violation of their ethical obligations, they may be subject to disciplinary action by the relevant bar association or regulatory body.