Montana is the only state that has passed a law that eliminated the at-will employment doctrine. Montana had a statute that provided for at-will employment. However, in 1987 the Montana legislature passed law called the Wrongful Discharge from Employment Act (WDFEA). It established that for employers needed good cause to fire employees who have completed their probationary periods of employment.

The interesting part of this was that when the Montana legislature passed its wrongful discharge law, it did not repeal its prior statute providing for at-will employment. However, in Whidden v. Nerison (1999), the Montana Supreme Court ruled that the Montana legislature repealed the at-will statute by implication, writing: “[W]e hold … that the WDFEA has superseded and impliedly repealed the at-will act.” The Montana high court also determined that the burden is on an employer to determine that an employee was discharged during a probationary period.