How does exclusionary rule apply in the context of a Fourth Amendment violation?

[Fourth Amendment] guaranty in the only effectively available wayby removing the incentive to disregard it." ( Elkins v. United States (1960) 364 U.S. 206, 217, 80 S.Ct. 1437, 4 L.Ed.2d 1669.)

However, the fact that a Fourth Amendment violation has occurred does not automatically require the application of the exclusionary rule. (See Herring v. United States (2009) 555 U.S. 135, 140, 129 S.Ct. 695, 172 L.Ed.2d 496.) "Indeed, exclusion has always been our last resort, not our first impulse. " ( Ibid . ) "We have repeatedly rejected the argument that exclusion is a necessary consequence of a Fourth Amendment violation." ( Id . at p. 141, 129 S.Ct. 695.)