Alright so digging a bit: At common law, “eavesdroppers, or such as listen under walls or windows, or the eaves of a house, to hearken after discourse, and th

Alright so digging a bit: At common law, “eavesdroppers, or such as listen under walls or windows, or the eaves of a house, to hearken after discourse, and thereupon to frame slanderous and mischievous tales, are a common nuisance and presentable at the court-leet; or are indictable at the sessions, and punishable by fine and finding of sureties for [their] good behavior.” [1] Very Early Eavesdropping law. but it wasn't prosecuted very often and faded from the common parlance: “Eavesdropping is indictable at the common law, not only in England but in our states. It is seldom brought to the attention of the courts, and our books contain too few decisions upon it to enable an author to define it with confidence.... It never occupied much space in the law, and it has nearly faded from the legal horizon.”[2] The first wiretapping laws were enacted by congress during world war 1: 40 Stat.1017-18 (1918)(“whoever during the period of governmental operation of the telephone and telegraph systems of the United States ... shall, without authority and without the knowledge and consent of the other users thereof, except as may be necessary for operation of the service, tap any telegraph or telephone line ... or whoever being employed in any such telephone or telegraph service shall divulge the contents of any such telephone or telegraph message to any person not duly authorized or entitled the receive the same, shall be fined not exceeding $1,000 or imprisoned for not more than one year or both”); 56 Cong.Rec. 10761-765 (1918). And you're right, that wiretaps weren't constitutional until 1968, but this doesn't discuss neighbors spying on neighbors. I think we found the same document: http://www.fas.org/sgp/crs/intel/98-326.pdf http://www.fas.org/sgp/crs/intel/98-326.pdf I'll ping my buddy to see if he can shed a little more light, but this is related to wiretaps, which is slightly different from eavesdropping. [1] 4 BLACKSTONE,COMMENTARIES ON THE LAWS OF ENGLAND, 169 (1769). [2]1 BISHOP, COMMENTARIES ON THE CRIMINAL LAW, 670 (1882)."