A common question asked by companies to many interviewees at many business job fairs after "when would you be available to start work?" is some form of this question: "are you currently under an contract or other obligation to any other employer, and if so can you tell me when that obligation ends?"The reason for this question is that the employer is making sure to protect itself from future claims of:

interference with a contractual

relationship

interference with prospective economic advantage

conversion

trespass to chattels

defamation