Gentlemen's agreement

A Gentlemen's agreement is an informal agreement between two or more parties. It may be written or oral. The essence of a gentleman's agreement is that it relies upon the honour of the parties for its fulfilment, rather than being in any way enforceable. It is, therefore, distinct from a legal agreement or contract, which can be enforced if necessary. The phrase's first recorded use was in 1888 in the Report of the Railway Accounting Officers published by the Association of American Railroads Accounting Division (page 337).

Negative connotations

The term has come to sound distinctly old fashioned, because of its implicit assumption that both parties will be gentlemen (and the old-fashioned nature of that phrase). After interwar politics in Europe the phrase has gained somewhat the connotation of an agreement easily broken.

In the United States, the term has also acquired negative connotations because it was used in various places in the early-mid 20th century to refer to unwritten discriminatory agreements relating to housing and employment of black and Jewish people. Because there was no written policy stating, for example, that black or Jewish families weren't allowed to reside in a particular town, there were no grounds for legal action.

Examples

Diplomacy

The Gentlemen's Agreement of 1907-1908 was a series of informal agreements between the United States and Japan. Japan agreed not to issue passports to citizens for travel to the United States, thus eliminating immigration. In exchange, schools in San Francisco, California, agreed not to discriminate against students of Japanese descent.
Britain signed a 'gentlemen's agreement' with Mussolini in 1937 over Naval access to the Mediterranean.
British Prime Minister Neville Chamberlain's discussions with Adolf Hitler culminated in the Munich Agreement of 1938 which is described in similar terms.
Hitler's agreement with the Austrian government in 1937 in which he guaranteed the country's independence.
In 1966, the Luxembourg compromise which ended the empty chair crisis recognized the possibility for any EEC-Member States (namely: France) to invoke its highest national interest to block a vote with qualified majority.

Politics

A gentlemen's agreement that once covered the City of Philadelphia by limiting the height of all buildings within the city to be no taller than the statue of William Penn that sits on top of Philadelphia City Hall. The Curse of Billy Penn is a coincidental anecdote in relation to the agreement.
The agreement by the United States press not to print photographs of President Franklin Roosevelt that showed his wheelchair or leg braces.
An agreement between the United States Army and Air Force prohibiting the army from operating combat jet airplanes.

Sport

In baseball, the unwritten rules that formed the baseball color line from 1887 to 1946.
In American football, an equally restrictive covenant against African-Americans existed in the NFL from 1933 to 1945.
In NASCAR racing, there was often an agreement between drivers to allow slower cars one or more laps down to pass the leader when the field came to a caution flag (this stopped all actual racing for position, effective at the start-finish line, due to a track hazard), instead of trying to keep said drivers behind. Here the phrase was more often used in its positive honourable connotation. As drivers more often started violating this agreement and racing hard to the caution flag, NASCAR changed its rules so that all racing would cease immediately when the yellow flag is displayed.
Professional Wrestling often relies on a "handshake agreement" between the performer and the promoter in regards to money and work dates. This is usually used in independent promotions that don't have the resources to draft legal agreements.
In association football, there is an unwritten rule that, in the case of an injury, if a player on the team opposite the injured player's team has possession, he/she will put the ball out of play (thus "giving it up" to the opposition) so that the injured player may be treated. Upon resuming play, the injured player's team is expected return the ball to the opposing team, allowing both teams to resume play as normal. The rule, though not officially imposed, is normally followed dutifully, however occasions where the rule is not observed have been known to lead to great animosity between the teams (and thus a more physical game). The most well known example of this is a FIFA World Cup 2006 match between Portugal and the Netherlands.

Industry

A now-defunct agreement between the major Japanese auto manufacturers to limit the maximum engine power of their cars to 280 PS (206 kW or 276 hp).
Boeing Commercial Airplanes signed exclusivity contracts with American Airlines, Continental Airlines, and Delta Air Lines in separate but nearly identical arrangements, regarding the supply of airliners. The European Union forced the contracts to be voided when Boeing merged with McDonnell Douglas, but all parties are continuing to adhere to the terms under gentlemen's agreements.
All major Japanese manufacturers voluntarily agreed to restrict the top speed of their motorcycles to 300 km/h (186 mph). The late 1990s saw "power wars" between various motorcycle manufacturers that culminated in Suzuki GSX1300R Hayabusa, the first production motorcycle to exceed this speed in 1999, and Kawasaki ZX-12R, designed to exceed 320 km/h (200 mph).
German carmakers put a 250 km/h (155 mph) speed limit on their automobiles except sports cars.

Culture

Gentleman's Agreement, a 1947 movie.