Definition of Zone theory
In law of trespass and nuisance, flights above one’s property may be actionable depending upon whether they are in the airspace of the lower zone or in the zone beyond the owner’s "effective possession”. Smith v. New England Aircraft Co., 270 Mass. 511, 170 N.E. 385.
Right of privacy is primarily restraint upon unwarranted governmental interference or intrusion into areas deemed to be within protected "zones of privacy.” Industrial Foundation of the South v. Texas Indus. Acc. Bd., Tex., 540 S.W.2d 668, 679.
That's the definition of Zone theory in Black's Law Dictionary 6th Edition. Courtesy of Cekhukum.com.