Duty of Loyalty
A director is required to act honestly and in good faith towards the organization. Directors should be forthright and open in all their dealings with staff, the public and regulators. If a director no longer has the time to commit to the board, lacks the expertise to make a decision or has a conflict of interest, they should say so.
Conflict of interest can be very difficult to avoid for directors, given that most are involved in many organizations and enterprises (and are valued for this.) Directors must avoid even the appearance of a conflict of interest. If in doubt, declare your interests, speak to the board chair, abstain from votes, and be prepared to resign if necessary.