There are examples in history where a firm that is not a government-granted monopoly is claimed to have a coercive monopoly, and anti-trust action has been initiated to resolve the perceived problem.
Advocates of a laissez-faire economic policy are quick to assert (barring private criminal conduct) that a coercive monopoly can only come about through government intervention, and defend these situations as non-coercive monopolies in which government should not intervene.