Pickering v. McCullough was a United States Supreme Court case that dealt with the issue of whether a public school teacher could be fired for expressing his political views. The case involved a teacher, Pickering, who wrote a letter to a local newspaper criticizing the school board for its handling of a bond issue. The school board fired Pickering for his letter, and he sued the board for violating his First Amendment rights. The Supreme Court held that the school board had the right to fire Pickering for his letter, but only if the board could show that Pickering's speech had interfered with the school's operations. The Court reasoned that the school board had a legitimate interest in maintaining an efficient and effective school system, and that Pickering's speech had interfered with that interest. The Court also noted that Pickering had not been fired for expressing his political views, but rather for the manner in which he had expressed them. The Court's decision in Pickering v. McCullough established the standard for determining when a public employee can be fired for expressing his or her political views. The Court held that a public employee can be fired for expressing his or her political views if the speech interferes with the efficient and effective operation of the public employer.

Justice Field delivered the dissenting opinion in Pickering v. McCullough, arguing that the majority had misconstrued the law and failed to consider relevant evidence. He argued that a contract between an employer and employee is not necessarily void if it does not comply with state laws, as long as both parties are aware of its terms and agree to them willingly. Furthermore, he noted that there was no evidence presented at trial indicating any fraud or misrepresentation on either side; thus, he concluded that the contract should be enforced according to its terms. Justice Field also disagreed with the majority's interpretation of Illinois' statute regarding contracts made by public officers for personal gain; instead, he argued that such contracts could still be valid if they were approved by two-thirds of a board or other governing body prior to being executed. Finally, Justice Field asserted his belief that even though Mr. Pickering may have acted unethically in entering into this agreement without first obtaining approval from his superiors, this did not invalidate their contractual arrangement nor entitle him (McCullough) to damages beyond those specified in their agreement