According to
William Blackstone, the original common law rule for dismissal of employees envisaged that, unless otherwise agreed, employees would be deemed to be hired for a fixed term of one year: "
The contract between them and their masters arises upon the hiring. If the hiring be general without any particular time limited, the law construes it to be a hiring for a year; upon a principle of natural equity, that the servant shall serve, and the master maintain him, throughout all the revolutions of the respective seasons; as well when there is work to be done, as when there is not: but the contract may be made for any larger or smaller term.". Over the 19th century, most states in the North adhered to the rule that the period by which an employee was paid (a week, a month or a year) determined the period of notice that should be given before a dismissal was effective. For instance, in 1870 in Massachusetts,
Tatterson v. Suffolk Manufacturing Company held that an employee's term of hiring dictated the default period of notice. By contrast, in Tennessee, a court stated in 1884 that an employer should be allowed to dismiss any worker, or any number of workers, for any reason at all. An individual, or a
collective agreement, according to the general doctrine of
freedom of contract could always stipulate that an employee should only be dismissed for a good reason, or a "just cause", or that elected employee representatives would have a say on whether a dismissal should take effect. However, the position of the typical 19th-century worker meant that this was rare. The at-will practice is typically traced to a treatise published by Horace Gray Wood in 1877, called
Master and Servant. Wood cited four U.S. cases as authority for his rule that when a hiring was indefinite, the burden of proof was on the servant to prove that an indefinite employment term was for one year. In
Toussaint v. Blue Cross & Blue Shield of Michigan, the Court noted that "Wood's rule was quickly cited as authority for another proposition." In New York, the first case to adopt Wood's rule was
Martin v. New York Life Insurance Company (1895). Justice
Edward T. Bartlett wrote that New York law now followed Wood's treatise, which meant that an employee who received $10,000, paid in a salary over a year, could be dismissed immediately. had held that New York law followed the general practice of requiring notice similar to pay periods. However, subsequent New York cases continued to follow the at-will rule into the early 20th century. Some courts saw the rule as requiring the employee to prove an express contract for a definite term in order to maintain an action based on termination of the employment. Later, in a 1980 landmark case involving
ARCO, the Supreme Court of California endorsed the rule first articulated by the Court of Appeal. The resulting civil actions by employees are now known in California as
Tameny actions for wrongful termination in violation of public policy. Since 1959, several
common law and
statutory exceptions to at-will employment have been created. Common law protects an employee from retaliation if the employee disobeys an employer on the grounds that the employer ordered him or her to do something illegal or immoral. However, in the majority of cases, the burden of proof remains upon the discharged employee. No U.S. state but
Montana has chosen to statutorily modify the employment at-will rule. In 1987, the Montana legislature passed the Wrongful Discharge from Employment Act (WDEA). The WDEA is unique in that, although it purports to preserve the at-will concept in employment law, it also expressly enumerates the legal basis for a wrongful discharge action. The doctrine of at-will employment can be overridden by an express contract or civil service statutes (in the case of government employees). As many as 34% of all U.S. employees apparently enjoy the protection of some kind of "just cause" or objectively reasonable requirement for termination that takes them out of the pure "at-will" category, including the 7.5% of unionized private-sector workers, the 0.8% of nonunion private-sector workers protected by union contracts, the 15% of nonunion private-sector workers with individual express contracts that override the at-will doctrine, and the 16% of the total workforce who enjoy civil service protections as public-sector employees. ==By state==