Yellow-dog contract – definition and meaning

A yellow-dog contract is an agreement that used to be used in American labor law to get employees to pledge that they would not join a union while working for their employer. If they did join a union during their employment, they would be fired. Until 1932, the yellow-dog contract was used widely. After the 1932 Norris-LaGuardia Act, it became illegal.

The yellow-dog contract, also known as a yellow-dog clause of a contract or an ironclad oath, was extensively used by US employers before 1932 to prevent the formation of trade unions.

Employers could take action against union organizers if their employees had signed a yellow-dog contract.

A previous federal law banning the use of yellow-dog contracts on the railroads – the 1898 Erdman Act – was struck down by the Supreme Court, which ruled that it was an unconstitutional infringement upon the freedom of contract.

Yellow-Dog Contract posterThe labor union was urging Pullman workers not to sign the ‘yellow-dog contract’, insisting that refusing to sign it did not mean that they were disloyal. (Image: adapted from

A yellow-dog clause within or appended to a non-disclosure agreement is used to prevent an employee from working for competing companies in the same industry.

According to, a yellow-dog contract is:

“An agreement used in United States labor law in which a prospective employee agrees as a condition of employment, not to join a labor union and to forfeit employment upon joining a union during the period of their employment.”

How the yellow dog contract emerged

After the American Civil War (1861-1865), the United States experienced a period of rapid industrialization. Many workers never had vacations, they had to work seven-day weeks, were paid extremely low wages, and were forced to work in dangerous and inhumane conditions.

Labor unions at the time were pushing for eight-hour days. Pro-business lawmakers and judges passed laws to prevent the unions from recruiting new members.

Pullman Strike 1894The Arcade Building in Pullman, Chicago, with strikers standing outside. The Illinois national Guard was brought in (in the image above they are facing the strikers) to guard the building during the 1984 Pullman Railroad Strike. (Image: Wikipedia)

In 1894, socialist Eugene V. Debs (1855-1926) led the famous Pullman Strike. All members of the American Railway Union went on strike after the Pullman Palace Car Company of Chicago slashed their wages by 25%.

When striking workers started attacking trains, President Grover Cleveland (1885-1889) brought in the army to put an end to the strike.

In 1895, when Pullman reopened its plant, every employee and prospective worker had to sign a yellow-dog contract. The employer wanted to make sure it would never have to face another strike.

The term – yellow-dog contract – was used by union members. A yellow dog was a worthless mongrel – the term was later applied to worthless people. Somebody who signed the contract pledging to never join a union was either worthless, or had a worthless job – the contract reduced workers to the status of yellow dogs (worthless things).

Yellow-Dog DemocratDo not confuse the term ‘yellow-dog contract’ with ‘yellow-dog democrat’, which is a nickname for an ultra-loyal Democratic Party voter. (Image: