The phrase "breach of privilege" refers to a situation where someone crosses the line of what is considered acceptable behavior, often in the context of an organization or institution. There are several synonyms for this phrase that can be used to convey a similar meaning, including misconduct, impropriety, violation, or transgression. These words all suggest that someone has broken a social or ethical norm, and may imply that there will be consequences for their actions. Other possible synonyms include malfeasance, corruption, or malpractice, which tend to suggest more serious violations of law or policy. Ultimately, the choice of synonym will depend on the specific context and degree of severity of the breach.