Preventive measures are the best way to handle difficult board members. Be sure that your agency’s goals for its board members are clear, and that they can combine their vision with the organisation. This reduces the number of situations in which a member’s opinion is not beneficial. However, if a problem occurs be proactive and do not overlook any bad behaviour. The longer you wait, the worse it gets.
Direct intervention is the initial step to initiate a conversation one-on-one with the person creating trouble. You should be professional and calm, but also clear and communicate your concerns clearly. If that doesn’t work, try an intervention in groups with someone who the board member respects and/or chair. You might also review the Values Statement of your organization and/or other governing documents for terms that can be used to define acceptable behavior, which includes treating people with respect and courteous manners.
Another option is to try to get the person to retire from the board (ideally by choice, but if required, by an unconvinced vote). This requires careful planning and preparation in advance of the meeting or discussion. Prepare a detailed answer to the major questions you’d like to address. Be assertive, but maintain an appropriate tone of voice.