What are the ethical concerns surrounding negative campaigning?

The ethical principles that apply generally to public life-rules about conflicts of interest, access to government, integrity, etc.-also apply to campaigns for political office. Why, then, treat campaign ethics as a separate topic? In practice, political campaigns represent one of the circumstances most likely to bring out the worst in people. Many candidates seem to subscribe to the theory that almost anything is allowable in order to get elected, because once in office, they will be outstanding public servants. Others, confronted with bad behavior on the part of their opponents, feel they must also cut moral corners just to compete.