Negative campaigning is trying to win an advantage by referring to negative aspects of an opponent or of a policy rather than emphasizing one's own positive attributes or preferred policies. In the broadest sense, the term covers any rhetoric which refers to an opponent, if only by way of contrast, but can also include attacks meant to destroy an opponent's character, which may veer into ad hominem.
Negative campaigning can be found in most marketplaces where ideas are contested. In U.S. politics "mudslinging" has been called "as American as Mississippi mud." Some research suggests negative campaigning is the norm in all political venues, mitigated only by the dynamics of a particular contest.
One of the most famous such ads was Daisy Girl by the campaign of Lyndon B. Johnson that successfully portrayed Republican Barry Goldwater as threatening nuclear war. Common negative campaign techniques include painting an opponent as soft on criminals, dishonest, corrupt, or a danger to the nation. One common negative campaigning tactic is attacking the other side for running a negative campaign.
Dirty tricks are also common in negative political campaigns. These generally involve secretly leaking damaging information to the media. This isolates a candidate from backlash and also does not cost any money. The material must be substantive enough to attract media interest, however, and if the truth is discovered it could severely damage a campaign. Other dirty tricks include trying to feed an opponent's team false information hoping they will use it and embarrass themselves.
Often a campaign will use outside organizations, such as lobby groups, to launch attacks. These can be claimed to be coming from a neutral source and if the allegations turn out not to be true the attacking candidate will not be damaged if the links cannot be proven. Negative campaigning can be conducted by proxy. For instance, highly partisan ads were placed in the 2004 U.S. presidential election by allegedly independent bodies like MoveOn.org and Swift Boat Veterans for Truth.
Push polls are attacks disguised as telephone polls. They might ask a question like "How would you react if Candidate A was revealed to beat his wife?", giving the impression that Candidate A might beat his wife. Members of the media and of the opposing party are deliberately not called making these tactics all but invisible and unprovable.
G. Gordon Liddy played a major role in developing these tactics during the Nixon playing an important advisory of rules that lead to the campaign of 1972. James Carville, mastermind of Bill Clinton's election, is also a major proponent of negative tactics. Lee Atwater, best known for being an advisor to presidents Ronald Reagan and George H.W. Bush, also pioneered many negative campaign techniques seen in political campaigns today.
Cathy Allen, president of Campaign Connection of Seattle, suggested negative campaigning might be the 'proper course' during political contests in the following situations:
Campaign organizers who invest their fortunes in negative approaches do so with considerable research to support the merit of their spending. In a 1996 study, researchers concluded that "the informational benefits of negative political ads possess the capacity to promote political participation, particularly among those otherwise least well equipped for political learning." Their testing found citizens who were aware of negative advertising were more likely to vote than those who didn't express recollection of such ads.
Martin Wattenberg and Craig Brians, of the University of California, Irvine, considered in their study whether negative campaigning mobilizes or alienates voters. They concluded that data used by Stephen Ansolabehere in a 1994 American Political Science Review article to advance the hypothesis that negative campaigning demobilizes voters was flawed.
Other researchers have confirmed similar positive results from negative campaigns. Rick Farmer, PhD, an assistant professor of political science at the University of Akron found that negative ads are more memorable than positive ads when they reinforce a preexisting belief and are relevant to the central issues of a marketing campaign. Researchers at the University of Georgia found the impact of negative ads increases over time, while positive ads used to counteract negative ads lack the power of negative ads.
Research also suggests negative campaigning introduces controversy and raises public awareness through additional news coverage.
Negative ads can produce a backlash. A disastrous ad was run by the Progressive Conservative Party of Canada in the 1993 Canadian federal election, apparently emphasizing Liberal Party of Canada leader Jean Chrétien's Bell's Palsy partial facial paralysis in a number of unflattering photos, with the subtext of criticizing his platforms. The ad was badly received and helped reduce the governing Conservatives to two seats.
Similar backlash happened to the Liberal Party in the 2006 federal election for running an attack ad that suggested that Conservative leader Stephen Harper would use Canadian soldiers to patrol Canadian cities, and impose some kind of martial law. The ad was only available from the Liberal Party's web site for a few hours prior to the release of the attack ads on television; nevertheless, it was picked up by the media and widely criticized for its absurdity, in particular the sentence "we're not making this up; we're not allowed to make this stuff up". Liberal MP Keith Martin expressed his disapproval of "whoever the idiot who approved that ad was," shortly before Liberal leader Paul Martin (no relation) stated that he had personally approved them. The effect of the ads was to diminish the credibility of the party's other attack ads. It offended many Canadians, particularly those in the military, some of whom were fighting in Afghanistan at the time. (See Canadian federal election, 2006)
Because of the possible harm that can come from being seen as a negative campaigner, candidates often pledge to refrain from negative attacks. This pledge is usually abandoned when an opponent is perceived to be "going negative," with the first retaliatory attack being, ironically, an accusation that the opponent is a negative campaigner.
While some research has found advantages and other has found disadvantages, some studies find no difference between negative and positive approaches. 
Research published in the Journal of Advertising found that negative political advertising makes the body want to turn away physically, but the mind remembers negative messages. The findings are based on research conducted by James Angelini, professor of communication at the University of Delaware, in collaboration with Samuel Bradley, assistant professor of advertising at Texas Tech University, and Sungkyoung Lee of Indiana University, which used ads that aired during the 2000 presidential election. During the study, the researchers placed electrodes under the eyes of willing participants and showed them a series of 30-second ads from both the George W. Bush and Al Gore campaigns. The electrodes picked up on the “startle response,” the automatic eye movement typically seen in response to snakes, spiders and other threats. Compared to positive or neutral messages, negative advertising prompted greater reflex reactions and a desire to move away.

In commercial advertising, various regulations prohibit false advertising and broadcast campaigns to promote potentially harmful activities, such as advertising tobacco products. Similar regulations have at times been proposed to limit negative political campaigning. Such restrictions have been proposed to regulate political advertising on television and radio, where negative claims might not be fully explained due to time constraints, and would expand disclosure requirements in printed political advertising.
In modern Western societies, however, proposed regulation of public speech is confronted by strong traditions favoring the open exchange of ideas, and by fundamental legal protections such as those of the U.S. Constitution. Practical considerations also weigh against regulation of political speech. Using rhetorical devices such as straw man or red herring arguments, a negative campaign can insinuate an opponent holds an idea without directly accusing the opponent of favoring those ideas. Within constitutional guidelines, few regulations could lawfully control candidates' statements in public appearances, where comments are often repeated in news broadcasts. To the contrary, public figures such as politicians enjoy weaker protection against false allegations than do average citizens.






