Most states in the US have at-will employment [0]. They don't even need to state a "probationary" period, they can simply fire anyone if they aren't performing.

Most states in the US have at-will employment [0]. They don't even need to state a "probationary" period, they can simply fire anyone if they aren't performing. [0]:http://en.wikipedia.org/wiki/At-will_employment http://en.wikipedia.org/wiki/At-will_employment