Although banned in the private sector in 1932 by the Norris-LaGuardia Act, yellow dog contracts were allowed in the public sector, including many government jobs, such as teachers, until the 1960s, from a precedent introduced in 1915 with Frederick v. Ownens.  Today, yellow canine contracts are the most common in the form of non-competition contracts. These are usually introduced by employers when they have a specific interest in preventing employees from working for a directly competing company and harming the future success of their business. By: Yellow dog contract in A Dictionary of Sports Studies “Yellow dog contracts do not always take shape as non-union agreements. They sometimes appear as non-competition prohibitions that expressly prohibit a worker from cooperating with a company`s direct competitor, which could harm his or her current employer. Yellow dog contracts are particularly advantageous for employers because they allow a company to take legal action against workers who engage in activities prohibited by the agreement. In the famous Pullman Strike of 1894, led by the socialist Eugene V. Debs (1855-1926), members of the American Railway Union went on strike against the Pullman Palace Car Company in Chicago when it reduced wages by 25 per cent. The union refused to work on a train that pulled a Pullman railcar, and seemed to be able to impose itself because almost all the trains that passed through Chicago were carrying Pullman cars. However, when striking workers began attacking trains, President Grover Cleveland (1885-1889) called on the U.S. military to end the strike. When Pullman reopened later in the year, all new employees had to sign contracts for yellow dogs.
Over time, yellow canine contracts became less and less important and by the beginning of the 20th century they were far from irrelevant. In fact, at that time, most employees were not very concerned about yellow dog contracts, and most union organizers cared very little about them. At the beginning of the 20th century, only two industries still used yellow dog contracts: coal companies and metal processing companies. A yellow dog contract (a yellow dog clause of a contract or an iron oath) is an agreement between an employer and a worker in which the worker is agreed as a condition of employment not to be a member of a union. In the United States, until the 1930s, such contracts were widely used by employers to prevent the formation of unions, most often by allowing employers to take legal action against trade union organizations. In 1932, yellow dog contracts were banned in the United States under the Norris-LaGuardia Act.   Comments from publications such as the United Mine Workers` Journal were well received by many union workers when they declared the actions of workers who were willing to sign the rights granted to each by the U.S. Constitution. , to call them “yellow dogs” and to compare them to slaves consenting to their employers.