A violation of a law, obligation, or promise. breach of the close.The common law trespass of entering another's land either unlawfully or without authorization. breach of duty. 1 The failure to perform a legal or moral obligation owed to a person or to the public. 2 The failure to act as required by the law. 3 The failure to exercise the care that a reasonable person would exercise in the same or similar situation. breach of fiduciary duty. The failure of a fiduciary to fulfill his duties wit...