Bava Batra 2 - Privacy Rights in a Courtyard
Observing one's activities is considered a form of trespass on his domain. Thus, the Rabbi required that fences and walls be built between neighboring properties to prevent such violations. Private places, such as a person's home, where intimate acts are constantly performed, are clearly protected by the law of privacy. A courtyard, however, is considered a semi-private place.
Partners who agreed to make a partition in a courtyard that they own jointly must build a wall in the center of the courtyard, each partner providing half of the land upon which to build. This is true, however, only if they agreed to a partition. Since courtyards are semi-private, one cannot force the other to do so, since visual trespass in this situation is not actionable.