One of the most important reasons is to reiterate that you are an ‘at-will’ employer – meaning an employee can be terminated at any time, and that an employee can quit at any time.
In Kang v. PB Fasteners, a long-term employee attempted to prove that his longevity at the company implied a contract. The U.S. Court of Appeals for the 9th Circuit rejected that claim, in part because the employer’s handbook stated all employment was “at will” and that employees could be terminated without cause at the employer’s discretion. The handbook also stated that it was not intended to “alter the at-will status of employment with the company.
Make sure the at-will statement is included in:
Your job application (with a signature from the candidate)
Your job offer letter
And in the Employee Handbook
Thanks to Jackson Lewis.