The phrase third rail is a metaphor

Metaphor

A metaphor is a literary figure of speech that uses an image, story or tangible thing to represent a less tangible thing or some intangible quality or idea; e.g., "Her eyes were glistening jewels." Metaphor may also be used for any rhetorical figures of speech that achieve their effects via...

 in politics

Politics

Politics is a process by which groups of people make collective decisions. The term is generally applied to the art or science of running governmental or state affairs, including behavior within civil governments, but also applies to institutions, fields, and special interest groups such as the...

 to denote an idea or topic that is so "charged" and "untouchable" that any politician

Politician

A politician, political leader, or political figure is an individual who is involved in influencing public policy and decision making...

 or public official who dares to broach the subject would invariably suffer politically.

Denotation

The third rail

Third rail

A third rail is a method of providing electric power to a railway train, through a semi-continuous rigid conductor placed alongside or between the rails of a railway track. It is used typically in a mass transit or rapid transit system, which has alignments in its own corridors, fully or almost...

 in a railway is the exposed electrical conductor that carries high voltage power. Stepping on the high-voltage third rail usually results in electrocution

Electric shock

Electric Shock of a body with any source of electricity that causes a sufficient current through the skin, muscles or hair. Typically, the expression is used to denote an unwanted exposure to electricity, hence the effects are considered undesirable....

. The use of the term in politics serves to emphasize the "shock" that results from raising the controversial idea, and the "political death" (or political suicide

Political suicide

Political suicide is the concept that a politician or political party would lose widespread support and confidence from the voting public by proposing actions that are seen as unfavourable or that might threaten the status quo. A politician who committed political suicide might be forced to resign...

) that the unaware or provocative politician would encounter as a result. Disagreement may occur over whether a specific issue is a "third rail" issue. What is considered a "third rail" issue varies by country. Third rail issues usually only die when politicians who have proven their credentials on related matters ignore the taboo and openly challenge the controversial issue.

Examples of usage in American politics

• Withdrawal of social security benefits
  Social Security (United States)
  In the United States, Social Security refers to the federal Old-Age, Survivors, and Disability Insurance program.The original Social Security Act and the current version of the Act, as amended encompass several social welfare and social insurance programs...
  
  .
• Criticism of the Israeli government
  Criticism of the Israeli government
  Criticism of the Israeli government, often referred to simply as criticism of Israel is an ongoing subject of journalistic and scholarly commentary and research within the scope of International relations theory, expressed in terms of political science...
  
  , its policies, and the state's existence.
• Gun control and firearm illegalization in Gun Politics
  Gun politics
  Gun politics addresses safety issues and ideologies related to firearms through criminal and noncriminal use. Gun politics deals with rules, regulations, and restrictions on the use, ownership, and distribution of firearms.-National sovereignty:...
  
  .
• Antidumping & Countervailing duty withdrawal.

External links

• William Safire: "Third Rail", New York Times Magazine, February 18, 2007