Are nonprofit board members required to conduct themselves in any particular manner? Yes.
Under well-established principles of nonprofit corporation law, a board member must meet certain standards of conduct and attention in carrying out his or her responsibilities to the organization. Several states have statutes adopting some variation of these duties that would be used in court to determine whether a board member acted improperly. These standards are usually described as the duty of care, the duty of loyalty, and the duty of obedience.
This resource discusses standards of conduct and features sample codes you might adapt for your own use.