What is false imprisonment? Under what conditions may a merchant detain a suspected shoplifter without facing liability for false imprisonment?

False imprisonment is defined as the intentional confinement or restraint of another person's activities without justification. False imprisonment interferes with the freedom to move without restraint. The confinement can be accomplished through the use of physical barriers, physical restraint, or threats of physical force. It is essential that the person being restrained not comply with the restraint willingly.
Stores are often sued for false imprisonment after they have attempted to confine a suspected shoplifter for questioning. Under the "privilege to detain" granted to merchants in some states, a merchant can use the defense of probable cause to justify delaying a suspected shoplifter. Probable cause exists when the evidence to support the belief that a person is guilty outweighs the evidence against that belief. Although laws governing false imprisonment vary from state to state, generally they require that any detention be conducted in a reasonable manner and for only a reasonable length of time.