When a prison guard stands accused of using excessive force in violation of the Eighth Amendment, what is the test for excessive force?

When a prison guard stands accused of using excessive force in violation of the Eighth Amendment, "the core judicial inquiry is . . . whether force was applied in a good-faith effort to maintain or restore discipline, or maliciously and sadistically to cause harm." Hudson v. McMillian, 503 U.S. 1, 7 (1992). In analyzing an Eighth Amendment excessive force claim, courts consider the following factors: (1) the need for application of force; (2) the relationship between the need and the amount of force used; (3) the extent of the injury inflicted; (4) the threat "reasonably perceived by the responsible officials"; and (5) "any efforts made to temper the severity of a forceful response." Id.