The answer for the blank part of the statement is employment-at-will. Employment-at-will is defined as a U.S type of contractual agreement where both employee and employer agree that the employee can be dismissed by the employer for any reason which is not illegal by law.
This type of contract is common in the late 19th century, but by the 20th century, most states add protections for the employees under any employment contract due to the power imbalance that occur in these kinds of contracts.
