Callaghan v. Myers was a Supreme Court case decided in 1979. The case involved a dispute between a union and an employer over the terms of a collective bargaining agreement. The union, Callaghan, had negotiated a contract with the employer, Myers, that included a provision for a grievance procedure. The employer refused to follow the procedure, and the union filed a complaint with the National Labor Relations Board (NLRB). The NLRB found that the employer had violated the National Labor Relations Act (NLRA) and ordered the employer to comply with the grievance procedure. The employer appealed the NLRB's decision to the Supreme Court. The Court held that the NLRA did not require the employer to comply with the grievance procedure, as the procedure was not part of the collective bargaining agreement. The Court also held that the NLRA did not give the NLRB the authority to order the employer to comply with the procedure. The Court concluded that the NLRA did not give the NLRB the power to enforce the grievance procedure, and the employer was not required to comply with it. The Court's decision in Callaghan v. Myers established that the NLRA does not give the NLRB the authority to enforce the terms of a collective bargaining agreement. The decision also established that the NLRA does not give the NLRB the power to order an employer to comply with a grievance procedure that is not part of the collective bargaining agreement.

In the dissenting opinion of Callaghan v. Myers, Justice Brennan argued that the majority’s decision was an incorrect interpretation of the law and would lead to a “harsh result” for taxpayers. He noted that Congress had intended to provide relief from double taxation when it enacted Section 1341, but instead this ruling allowed for double taxation in certain circumstances. He also pointed out that if taxpayers were not able to rely on their returns as filed, then they could be subject to penalties or other sanctions even though they acted in good faith reliance on those returns. Finally, he argued that allowing such a harsh penalty would discourage people from filing accurate tax returns and thus undermine public confidence in our system of voluntary compliance with tax laws. In conclusion, Justice Brennan believed that Congress did not intend for taxpayers who relied upon their original return filings should be subjected to additional taxes due solely because of changes made by IRS auditors after-the-fact; therefore he dissented from the majority opinion which upheld such a practice