Preventive measures are the best approach to handle difficult board members. Be sure that your agency’s goals for its board members are clear and they are able combine their vision with the organisation. This will reduce the instances in which the advice of a member of the board can be counterproductive. If there is a problem be quick to address it and don’t put off bad behavior. Hesitating only makes it worse.
Direct intervention is the initial step – a one-on-one meeting with the person who is causing trouble. It is important to be professional and calm, however explicit in the discussion and clearly articulate your concerns. If this doesn’t work, consider an intervention in groups with a board member who the board is comfortable with and/or the chair. It may be beneficial to go through the values statement of your organization or other documents that govern the organization for words that could be used as a standard for acceptable behavior, such as treating people with respect.
Another option is to ask the person to quit the board (ideally by a voluntary decision, but if necessary you can do it through a vote in confidence). This will require careful planning and preparation ahead news of the meeting or conversation. For example, make sure you are aware of the major issues you wish to discuss and have an organized response in place. Also ensure that your tone is polite but firm. Don’t be afraid to be assertive.